Sometimes when almost anyone can get into an airport lounge, no one can. Here's what to know before you count on using this credit card perk. Years ago, there were business travelers and there were leisure travelers, and nary did the perks of the high-flying former trickle down to the economy-focused latter. Airport lounges that offer cozy chairs, free buffet spreads and an open bar while you wait to board? Those were reserved for the business traveler in the tailored suit. In recent years, the lines have blurred. The airport lounge slowly became not only a haven for the business...