You've passed those doors along an airport concourse, the ones with discreet plaques that say "Admirals Club" or "Sky Club." If you didn't already know, they're airport lounges. Unless you've been inside one, however, you may wonder who and what are inside. The answer: mostly frequent flyers, enjoying an oasis of comfort and support in the airport's otherwise-hostile environment. The downside is that getting in can be expensive—although maybe not as expensive as you might think.
If you travel only a few times a year, you might have a tough time justifying the cost of an annual or longer membership. But some programs let you in on one-day or short-term passes. And the advantages are significant.