NEW YORK (FORTUNE) - Let's just get this out of the way - work is not supposed to be fun. There is a reason that what we do each day shares its name with the biblical personification of hopeless pain and suffering, Job himself. Yet at the Best Companies to Work For, employees don't just enjoy their work, they brag to total strangers about how great they have it.

I wanted to be that happy. So I got a job -- four of them, in fact. I scaled hydrocarbon-cracking towers in Corpus Christi; pushed five-foot stacks of suitcases down carpeted halls in Washington, D.C.; folded T-shirts at a New Jersey mall; and delivered box after box on the streets of Brooklyn. My Tocqueville-on-meth tour yielded some surprising results.

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For starters, most of the things that make a workplace great turn out to cost employers absolutely nothing. Next, a great workplace benefits more than just employees: Over the past five years the stocks of the four companies I worked at trounced the market, up a compounded 24 percent vs. the S&P's 1 percent gain. And last, when folding T-shirts, a sharp snap at the end gets you a really nice crease.

"Feel free to tell me today what I'm doing wrong," I say to Robert Preston, the front services manager at the hotel.

"You're leaning on the concierge desk," he replies. Preston's domain is the ten yards that guests cover when they go from their car to check-in. As a bellman, I'm someone he's responsible for. I stand up straight and try to look a little less sweaty in my Four Seasons uniform of black turtleneck and pleated poly-wool pants. Preston, 30, is wearing a crisp suit and has a transparent earplug that relays commands from the front desk; his mike is in his sleeve. I'd like one of those, but now doesn't seem the time to bug Preston about it, so I scurry behind the desk to wait for bags to come in.

My first luggage run is up to room 471 to help a couple from Texas check out. When my partner, Samuel Balcha, and I get to the room, I start lugging their hard-sided suitcases onto the cart. The heavily frosted wife stops me. "We just saw on the TV where they were canceling flights at Dallas - Fort Worth," she says. We wait as they decide whether they're going to check out or not. There are loads of bags to deliver still, but Balcha calmly stands by the cart as if these are his only customers.

The Four Seasons wants its staff to be relaxed, regular people, so they're given leeway to do what they think is right. Balcha is a quiet 25- year-old who has been at the hotel for nearly five years. He's a natural at acting natural: "Take your time, it's no problem," he says. "How was your stay?" When the couple find that the flight is on and we start pushing the bags down the hall, they give him a nice tip -- but ignore me. I don't blame them. I haven't mustered up any warmth. I'd ignore me too.

"We want individuals to think and be natural rather than just robotically doing things," says Christopher Hunsberger, 47, the general manager. We're sitting in the employee lunchroom, a subterranean café that today is serving a buffet of meat loaf, peas, corn, and some sort of lasagna. After a big wedding or meeting at the hotel, unserved desserts make their way down here. "We have standards, but they're not rigidly defined."

I see that while I'm out working the door with Endale Tessema. Tessema, 48, has been with the hotel for 23 years, yet he's still the rookie of the four-person doorman staff. He says he can recognize by name thousands of people who have stayed at the hotel over his decades. He does pretty much as he pleases -- no canned speeches, no formal way of opening the door or lugging the luggage. He just makes it up as he goes, and he says the people in charge learn from him. "The managers, instead of coming in and imposing things on me, they come in and learn how things work," he says. "If they want to change it, they'll change it later. They have to learn first."

That policy, those in management say, helps ensure that ideas from the bottom bubble up -- and that the hotel's personality flourishes. Back on bag duty, it's starting to feel pretty robotic lugging suitcases from room to room, but Balcha seems to dig it. I'm guessing the tips help. I head across from the lobby to a room where about a dozen workers with headsets are on the phone. There's little remarkable about this spot until Noel Merainer, the hotel's 28-year-old "director of revenue management," tells me what it used to be like.

Until 2004 the space was divided in two, with one group acting as operators and phone-support folks and the other handling room reservations. Merainer took down the wall between the two, figuratively and literally. Despite working in a chain, which typically would formalize processes, he had no problem getting it done. All the operators began fielding every kind of call -- reservations, guest requests, spa appointments -- and enjoying the variety.

All along the way, he kept asking the workers their opinions. "Some employees have been at this since I was in grade school," he says. "They are the experts on a lot of things that were new to us as managers." Today the idea is spreading through Four Seasons as it embarks on a major expansion, with 26 properties under development on top of the 68 now controlled by the company. (Wall Street hopes the growth will finally goose the stock, which is down over 30% in the past year after running into currency issues.) In fact, Merainer is on his way to Palo Alto in a few weeks to help the staff of a new Four Seasons there implement his idea.

I, on the other hand, spend the rest of the day manning the front door. This requires constant neck-swiveling between lobby and driveway. In the spirit of letting ideas bubble up from the bottom, I consider suggesting a rotating platform for doormen to stand on. But only if they call it a Lazy Dan.

Things start early -- and right on time -- at FedEx. The "cans," giant metal bins full of packages that fit like a shoetree into FedEx planes, begin showing up just after 6 A.M. The couriers lead one another in a group stretch. Then, right at 8 A.M., the conveyer belts start and the packages cruise down at a rate of 3,300 per hour. Drivers do all the sorting here, separating packages by zip codes. I help.

A bit. As the iPods and L.L. Bean boxes build up steam, I let a few slip by without inspection. (And for that I'd like to apologize to the residents of zip code 11218 for delaying Christmas.) When the belt is cleared, Nicky Cava and I head out.

Cava, 39, is a nine-year veteran of FedEx. He's beaming as he belts out tunes and loads van 237610: "My truck," he says proudly. He's not kidding: It almost is. "Once he leaves this station, he's his own boss," says Shelley Simes, Cava's senior manager. For all FedEx's clock-watching and efficiency, the company is remarkably hands-off.

Cava's territory is the Kensington section of Brooklyn, a neighborhood of beautiful, if rundown, homes and massive apartment complexes. It's up to Cava to set his route. And he knows it by heart: As he's showing me the ropes, he's joking with locals with the ease of a neighborhood bartender. He also has the ability to know exactly what's in each package. "See this?" he says, holding a generic FedEx envelope. "This is a passport. This woman is probably going to Jamaica for the holidays and needs her passport." I ring the bell, and she opens her door just enough to grab the package and thank me in a Jamaican accent.

Cava's a naturally optimistic guy, but when he talks about his employer, he might as well be discussing corporate Shangri-la: When he's cold, he's given gloves. If things are getting backed up, someone helps. His boss stresses safety. When one of his four kids was sick recently, FedEx's medical coverage helped with the bills.

As for the argument that corporate America simply can't afford to be that generous? A $1,000 investment in FedEx when it went public in 1978 would now be worth $106,000. And while a ballooning 401(k) is one powerful tool for retaining employees, what keeps Cava happy is the fact that he's expected to decide what's right with his day.

So what to me seems like unnecessary circling of the same blocks is actually Cava computing in his head which routes are the best to get the priority packages done first, then the standard deliveries, and finally how to get back to the office quickest. There's no GPS satellite charting his progress; all he needs to do is make his deliveries fast and to the right people. He makes his own calls about where to leave a package if no one is home and when to demand a signature -- even if the person has okayed it to be delivered without one.

While I've mastered the art of balancing packages on moldings as I'm pushing buzzers -- "Use ledges to your advantage," Cava intones -- or running up stairs and pounding on people's doors, the scanner is turning out to be a bit of a problem. Cava takes to standing in front of me holding a package as he talks me through the process: "Point it at the bar code, remember? No, not that one. Lower!" Cava swears that "the only way you lose your job at FedEx is if you make yourself lose your job." Judging from today's performance, I think I'd come close.

I'm perched on the rickety wooden steps of a heavy oil cracker -- a 24-story tower of darkened pipes, scaffolding, and steam that takes residual crude oil, heats it to 1,000 degrees, and runs it over a claylike catalyst, which breaks -- or cracks -- the oil's hydrocarbon chain. The cracker is ridiculously loud, so I just guess what instructions my supervisor, Robert Jasso, is screaming at me. I suspect they involve the 50-pound bags of walnut shells we're feeding the unit to keep it clean. Real walnut shells.

This 524-acre site, which looks like the set of some dystopian sci-fi movie, houses the original of Valero's 18 oil refineries, which make it the largest refiner in North America. Back in the control center -- a room full of beeping monitors and ten guys in blue flame-retardant suits swapping fishing stories -- talk turns to Valero's stock. Each of these workers knows the price (a split-adjusted $53.44) and has an opinion about where it's going. "I'm going to wait until it drops into the mid-40s, then buy as it goes up with Exxon Mobil and Conoco," says Denny Weikleenget, 49, a former commercial fisherman. "Yeah, it will float with Exxon," says shift superintendent Don Thierry, 54.

Stock and option grants are doled out to employees deep into the organization. Those shares -- along with the company stock that employees receive in their 401(k) -- are a big reason that Valero people are happy. The company counts 400 employees whose stock or 401(k) tops $1 million (they're called "Valero-naires"). "Shoot, the stock's done so well that at 32, I've got more in my 401(k) than my dad does," a technician named Chester Bullard tells me.

"Everyone wants to work here," says John Sheffield. And not just for the money. At 28, he's been with Valero for five years but has seen other refineries in one of his former jobs as a contractor. At Flint Hills, a neighboring refinery owned by Koch Industries, employees aren't allowed to chew or dip tobacco, he says. Here, "they want us to quit" but don't ban it. Plus, he says, management never sacrifices safety to save time. "Nothing is cutthroat here," he says.

I see what he means at about 4:45 A.M., when the next shift starts filtering in and the night workers update their replacements on what's happening. There's no timecard punching or sprinting to the door. The room feels like one big water cooler meeting ... where the hottest office gossip is about the state of the naphtha and iron sulfite. The guys I'm embedded with are coming off four 12-hour nights; now they'll have four days off before they come back to four 12-hour days. That's not a bad schedule: As the Valero folks point out, when you add in vacation (and ignore the fact that each shift is 12 hours long), that's less than half a year's work for a year's pay.

"Everywhere else I've worked I've been yelled at for turning up the music," says Robbie Dulaney, just 23 but already a veteran of such mall stores as PacSun and Journeys shoes. "But not here; they're like: Turn it up!" So he does, blasting the Faint and Murder City Devils at the teens and the parents of teens who are doing last-minute Christmas shopping at Hot Topic, a chain of over 650 mall stores that sell rock-and pop-culture clothes, music, and jewelry to teens, preteens, and the moms who control the credit cards.

Dulaney has black hair and wears the shrunken slacks and sweatshirt of a proper hipster, yet he jumps at the chance to help anyone at the store. Such is the dichotomy of Hot Topic: too-cool workers who aren't too cool to sell. With an expected $720 million in sales this year, Hot Topic has to be able to extend beyond just rock snobs. So it offers a whole wall of rock T-shirts, Nightmare Before Christmas figurines, Tinker Bell T-shirts, and plenty of jewelry for the pierced generation. (Employee Amy Collins, 21, tells me that the Monroe -- a stud placed just above the lip, like Marilyn Monroe's beauty mark -- is "the new bellybutton ring." Parents: Tell your kids you read it in FORTUNE and win sure-fire props!)

Folding T-shirts, which is what I spend my day doing, is not so rock & roll. But the real action, it turns out, isn't in the stores. Rick Littlefield, the unflappable 28-year-old store manager, explains that everyone's expected to attend rock shows as frequently as possible. Employees get their tickets reimbursed as long as they fill out a fashion report: What did the band wear? What did the kids in the mosh pit wear? How many were sporting bandannas?

Hot Topic makes its employees the first responders of cool -- a task that suddenly gives some real importance to what could be a tedious job. Employees are expected to call buyers with tips, access that is almost unheard of in retail. That makes the salespeople feel as though they're not just selling products, but picking them. It also gives them a bit of attitude about inventory.

Hot Topic's same-store sales in December were down 6% from last year, and Dulaney isn't shy about suggesting one of the culprits. Pointing toward some baggy hoodies hanging on a high peg, he pronounces the look dead. "Kids want a more do-it-yourself look," he says. "And in general, they're going for a less baggy, more fitted aesthetic." Plus, girls want fur around the collar. The buyers, he says, aren't responding fast enough.

As the store fills with teens awkwardly forming small groups, my job hopping winds to a close. The shock of my four stints wasn't that these companies were so extraordinary, but that other companies can't -- or just don't -- do the simple things that make employees happy. Forget brain surgery; this is barely baking-soda-volcano science. At every stop my fellow workers talked about bosses either leaving them alone or being there for them. They discussed work-life balance, stock options, and sick days. As for me, I just want to reassure FORTUNE that I don't in any sense see my job as being at all Job-like (Of course, I've got to say that; I don't think any of the companies I worked for would hire me back).

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