(FORTUNE Magazine) – A good hotel is a surrogate mother and business partner rolled into one. At the top chains, you're paying for a blend of pampering and no-nonsense service that should leverage your time in hundreds of immeasurable ways, despite unfamiliar circumstances. To find out which hotels offer the best service, FORTUNE sent me on the road to rigorously evaluate and rank six top business chains: Fairmont, Four Seasons, Mandarin Oriental, Marriott, Park Hyatt, and Ritz-Carlton. (My credentials: an infinite capacity to complain, nitpick, and operate a stopwatch around the clock.) And while these chains may seem similar when it comes to rates and reputation, I found some dramatic differences among them, to say the least.

During my two-night stay at a representative hotel from each company--some East Coast, some West Coast--I performed a litany of tests, from the routine (a late-night suit press) to the "emergency" (a conference room in 15 minutes) to the absurd (a 3 A.M. plea for pancakes). Then there was the 3:15 A.M. call for a peanut butter and pickle sandwich. At 3:30 A.M., a pot of coffee...in other words, I pushed the envelope. God forbid you ever need to abuse a hotel as I did, but it's certainly worth knowing who withstands such pressure best. This year's winner: the Four Seasons, for its unshakable ability to handle both the mundane and the monumental.

Of course, choosing a hotel isn't strictly science. A hotel can bolster your business image--and depending on what you want to project, different chains will work better or worse. Usually, a final impression is composed of thousands of mini-impressions. Following, an overview of what you can expect when you arrive at the door of your next hotel room:

FOUR SEASONS no one beats the Four Seasons for sheer sumptuousness--book-matched blond wood in the walk-in closet, Frette sheets, and a bathtub you can swim laps in, for starters.

The Four Seasons' room service was the best of the bunch, serving up food that puts most good restaurants to shame. Even my base request for a burger was met with grace. A tasty, juicy example was presented on a lightly toasted bun with a heaping portion of golden fries that were long and lean and shapely--the sexiest French fries that I've ever seen (or consumed). And the valet got an A+: I called at midnight and had a perfectly pressed suit back in 30 minutes.

This chain has mastered the small touches, like the switches by your bed that electronically control the curtains from across the room. And the all-marble bathroom was a beauty, complete with separate glass stall shower, a night-light to prevent midnight stumbles, and a remote-controlled TV for channel surfing from the tub. (And should you suddenly have a desire to call your broker after checking the stock quotes on CNN, there's also a phone within easy reach.)

In fact, the only problem I had was trying to find a problem for the purposes of this article. Here's what I finally stooped to: Having been informed at check-in that the bathtub fills in 60 seconds (a bit of front-desk bragging), I timed it. My trusty stopwatch revealed this to be an exaggeration. I complained, and sure enough, two engineers arrived and slaved over my bathtub--only to have it still take two minutes and 38 seconds to fill. Don't say I didn't warn you.

RITZ-CARLTON Aesthetically, Four Seasons and Ritz-Carlton are two different worlds with little in common but quality. The Four Seasons is sleek and postmodern; at the Ritz-Carlton, the look is Louis XIV. The Four Seasons' staff clips along with brisk efficiency, while Ritz-Carlton favors the personal touch: When my complaints to the manager got me an upgrade to a room with views of Central Park, all my belongings were moved without my supervision and arranged exactly as they had been in my back-alley room--down to the last paper clip. I imagined the poor chambermaid measuring the distance from the clip to the edge of my desk.

Even though the Ritz-Carlton logo was emblazoned on everything from the bathrobes to the bottled water, this was the only chain that didn't feel like a chain. The armoire holding my TV looked as if it was hand-crafted by carpenters in the south of France. And I could swear that the print of a rosy-cheeked young mother playing with her child beside a tranquil lake was selected for my room by my dignified Aunt Betty.

That's the Ritz-Carlton--it's a lot like a visit to the home of a well-off older relative, where the bathroom is a little chilly, everything's slightly faded from years of over-zealous cleaning, and the food's about as good as Aunt Betty's. Yet while these flaws were mildly endearing, in the end they lost out to the Four Seasons' relentless sense of decadence and indulgence.

MARRIOTT Here's where we make our first significant leap downward in quality. These comfortable but bland McRooms won't be confused with those in either of our top choices--no more charming prints on the walls, no more imported chocolates on your down pillow.

Business-related services were spotty at best. When I said that I needed my suit pressed by early the next morning, a different staff member called me every five minutes to say that someone would pick it up right away. After a half hour of this, they finally fessed up and admitted that they couldn't accommodate me. And when I phoned the concierge to say that I needed a conference room for an impromptu meeting, all he could talk about was the cost of items in the hospitality suite's wet bar. Perhaps he was hoping that my colleagues and I would spend our time drinking to boost Marriott's profits instead of talking about our own.

All this contrasts curiously with the Marriott's stellar nonbusiness services: When I complained about my suit debacle, the genuinely concerned manager told me my second night would be free, "if that's acceptable to you." And their peanut butter and pickle sandwich--with its artfully fanned-out slices--was the loveliest of them all.

MANDARIN ORIENTAL This highly distinctive Asian newcomer is creeping into the United States via Hawaii and San Francisco. Set on the top 11 floors of a massive glass-and-stone office building, the Mandarin San Francisco has all the amenities you'd expect, plus a few unique touches. Staying here was like traveling to a far-flung land--even the cleaning fluids used in the bathroom smelled exotic.

At the Mandarin, when the maids turned down the bed at night, instead of putting mints on my pillow, they placed a delicate white cotton mat at the bedside, with a neatly arranged pair of Thai silk slippers on top of it. And the room's desk had a beautiful hand-painted porcelain "friendship" lamp with three-dimensional Chinese figures gracefully scaling its sides.

Unfortunately, the Mandarin's charms ended at its international personality; the hotel was consistently unable to handle any kind of eccentric request. This was the only hotel, for example, that failed my peanut butter and pickle test (only a smear of peanut butter on toast, with nary a dill in sight). When I ordered a vanilla float, I had to explain how to make it: Coke and vanilla ice cream. A few minutes later I got a call asking if it was okay to use Pepsi instead. And only one other hotel (the Hyatt) brushed off my 4 A.M. request to fetch some items from the drugstore. Although the staff failed my more abusive tests, the Mandarin is a luxurious choice if your service needs run to the basic.

FAIRMONT The gorgeous Italianate palazzo exterior of their flagship San Francisco hotel is a sight for sore eyes after a six-hour flight. But once inside, I realized that this place is resting on its laurels. My shabby, musty, light-blue room looked as though it hadn't been renovated in years. It did have one, um, unique perk: Mirror Go Lightly, a gadget that shows you how you look in different lighting environments by virtue of pink and green plastic pieces that slide over the mirror's fluorescent bulbs. I kept searching for the boardroom setting.

The Fairmont's overworked employees were highly erratic. Every time I called downstairs, I was placed on hold for several minutes. One manager didn't return my phone call and barely paid attention when I confronted him in person. When I pointed to the AAA five-diamond award hanging behind him and asked how the hotel managed to snag that honor, he snapped at me and pointed to the small print, which indicated that it was an old award. ("We've decided to not maintain that rating," he said. "It costs too much.")

To be fair, their valet was excellent, and they got me a free conference room (no phones) without the usual hemming and hawing. And most impressive, when my laptop broke down on a Saturday, the concierge doggedly made 35 phone calls until he found someone to rent me a new one.

PARK HYATT The New York Park Hyatt was in the same league as the other chains when it came to service, but its rooms were another story. Mine was done up in ultra-depressing shades of beige from floor to ceiling, and the only escape from the mothball smell was in the room's bizarre kitchenette, which reeked of spoiled cheese. I felt as if I were in the motel where Timothy McVeigh allegedly planned the Oklahoma bombing. And then I saw the bathroom: The circular sea-green shag carpet was a particularly seedy touch. A phone was hanging from the wall by a thin wire, threatening to splash into the toilet bowl below at any second. Behind the mildewed shower curtain, the showerhead half-heartedly spat luke-cold water at me, no matter how I twisted the dials.

But: The staff performed decently on all my tests. And when I complained about my disappointing surroundings to the manager, he explained that New York City's ownership of this particular hotel makes running it a bureaucratic nightmare. He was partially right: I spot-checked a couple of rooms in the San Francisco Park Hyatt, and while they were somewhat unattractive, they were at least standard-issue rooms.

After my coast-to-coast, 12-day, eight-room undercover whirlwind mission, I had to agree with Callaway Golf CEO Donald Dye, who said, "If everyone stayed at the Four Seasons, no one would ever have any complaints about hotels." Unless you're a tub-timer, that is.