(Business 2.0) – Boeing Everett, WA

The Tour: The theme is grandeur, and it's no delusion. Some of the world's biggest machines--the 747, 767, and 777--are assembled here in the largest factory in the world (110.6 feet high, spanning 98 acres). From the third-floor observation deck, you'll see overhead cranes moving giant plane parts. On the floor, mechanics join wings to fuselage with lasers and thread wire through the planes (171 miles of it, in the case of a 747-400).

Highlight: Though you may not notice it, the planes are actually crawling an inch or two an hour across the factory floor. Last December, Boeing began moving the planes to the parts rather than vice versa as a time-saving measure.

When and Where: Tours run once an hour on weekdays from 9 to 11 a.m. and 1 to 3 p.m. To get to Boeing's Everett Tour Center, go north from Seattle on Interstate 5, then west on Highway 526.

Reservations: Recommended in the busier summer months, though advance tickets cost $10 per person. Otherwise, admission is $5 for adults, $3 for children under 15. Call 800-464-1476.

Kohler Kohler, WI

The Tour: As a major maker of bathroom fixtures, Kohler has a reputation for cranking out products whose form is far more attractive than their function--so it's appropriate that this tour starts in the company's design center. From there, retired Kohler factory workers take you out onto the floor to show you how vitreous china is molded and then fired in giant kilns.

Highlight: The Kohler Waters Spa at the American Club resort is only a few steps away. There are four great golf courses, but you may prefer to luxuriate in a high-style Kohler tub for a water massage or milk bath. (OK, we admit it, the tour is really an excuse to end up here.)

When and Where: The three-hour tour departs from the Kohler Design Center weekdays at 8:30 a.m. Kohler is off Interstate 43 about an hour north of Milwaukee.

Reservations: Required. Call 920-457-3699.

Airborne Express Wilmington, OH

The Tour: Logistics has been raised to an art form here at the sorting facility of Airborne Express. Visitors get a rare glimpse of an operation that makes most businesses seem about as complex as finger painting: By the end of the night, more than 1 million packages will have moved their way through the facility and been loaded on planes bound for destinations around the globe.

Highlight: Pick out a package and follow it through the night as it's routed along a 15.5-mile network of conveyor belts and sorting machines.

When and Where: The two-and-a-half-hour tour starts at 11:30 p.m. every weekday at the administration building of Airborne's private airport, off Interstate 71 between Columbus and Cincinnati. (Daytime tours are also available, but don't bother--the real action happens at night.)

Reservations: Call 937-382-5591, ext. 2536, two to three weeks in advance. A photo ID1is required.

Scharffen Berger Chocolate Berkeley, CA

The Tour: Forget Hershey in Pennsylvania. That's now an amusement park, not a bona fide factory tour. But here in this little brick plant, you can see how Robert Steinberg and John Scharffenberger are quietly trying to change American tastes. They make no milk chocolate here--only the cacao-rich dark variety preferred by pastry chefs. Visitors are required to don caps and earmuffs; noses are unfettered, thankfully, because the smell is glorious. Those enamored with cutting-edge technology may find this tour a bit disappointing: The techniques employed here are ancient, and some machines, like the melangeur, which grinds the cocoa butter from cacao beans, are 80 years old. But at least the company's marketing is up to date: Connoisseurs of fine chocolate willingly fork over $4 for a 3-ounce bar.

Highlight: What else? The taste-testing of three kinds of chocolates at the tour's start.

When and Where: Hour-long tours are offered daily at 10:30 a.m., 2:30 p.m., and 3:30 p.m. Get off Interstate 80 at the Ashby Avenue exit in Berkeley and turn left on Seventh Avenue, then right on Heinz Street.

Reservations: Recommended, but the tour is free. Fill out an online request form at www.scharffen-berger.com/factory/onsite_tour.html or call 510-981-4041.

Walt Disney World Orlando, FL

The Tour: Alas, on Disney's Keys to the Kingdom tour, you won't see costumed employees singing "Hi-ho, hi-ho, It's off to work we go." (You might, however, see an off-duty Cinderella smoking a cigarette, which is why this backstage pass is limited to those 16 and over.) Learn the tricks that put the "magic" in Magic Kingdom--the talking head in the Haunted Mansion's Seance Room is no hologram, for instance; it's looped film of a woman projected on a faceless white statue--and then take the rides to see whether you still enjoy them after the secrets have been revealed.

Highlight: A peek at the "utilidors," Disney's cutesy name for the park's below-the-scenes tunnels. Interestingly, they aren't actually underground, but rather are on the first floor of the complex that Disney built in the late 1960s atop a Florida swamp.

When and Where: The four-and-a-half-hour tour departs from Main Street USA every day at 8:30, 9, and 9:30 a.m.

Reservations: Recommended. Tickets cost $58 on top of regular park admission, but lunch is included. Call 407-939-8687. --LOIS GILMAN AND BRIDGET FINN