Airport lounges promise a civilized retreat from the noise, crowds, overpriced drinks, and general discomfort of the concourse—for a price. We peer behind the doors of dozens of lounges at home and abroad to find out what they deliver and whether they're really worth the money.

In that nearly forgotten era of the jet set, an airport lounge conjured images of the idle rich killing time over champagne and card games—think Elizabeth Taylor and Richard Burton in the 1963 movie The V.I.P.s. When American Airlines opened its first lounge 70 years ago, at what is now New York's LaGuardia, there wasn't really much need for one: Few people flew, there was no security to speak of, and travelers could show up mere minutes before their departure without fear of losing their seat. Instead, a lounge was a way for the airline to spoil its best customers, and the only way in was by invitation.

How things have changed. Most of today's lounges aren't as exclusive, and they are the last refuge (apart, perhaps, from the airport chapel) from the drone of televisions, the smell of fast food, the obstacle course of wheelies, and the chaos of the concourse. "The democratization of air travel is complete, and we're headed down the other side," says Kevin Mitchell, chairman of the Business Travel Coalition, an organization that represents corporate fliers. "The lounge offers a bit of an escape from the nightmare on the other side of the security checkpoint."

Although many travelers don't realize it, you don't have to fly first or business class—or be an elite member of an airline frequent-flier program—to gain access to most lounges today. True, some are still the sole preserve of premium-class passengers, and many foreign carriers don't welcome visitors into their lounges. But getting into countless others at airports around the world requires and forking over about $50 at the door, joining a lounge club program, or making a reservation online.

Before you rush to buy your way into the next lounge you see, though, be forewarned: Not all of them are created equal. Some are spacious and stylish sanctuaries offering complimentary premium cocktails, hot meals, showers, and quiet zones free of children and cell phones. Delta has even teamed with the PGA to offer putting greens at its facilities in Atlanta and seven other U.S. cities. Others, however, are little more than cramped and dingy spaces without bathrooms, where the free offerings are limited to peanuts, crackers, and watered-down coffee. So always do a little research at a Web site with lounge reviews—such as loungeguide.net or flyerguide.net—before you leave for the airport.

Here then, is our ultimate insider's guide to the not-so-exclusive world behind those heavy double doors.