Airports are amazing places. Thousands of people pass through them every day traveling to all corners of the planet. Considering the number of restaurants, shops and services they provide, some airports even function like small cities. But like any buzzing metropolis, the crowds can feel overwhelming. A secluded airport lounge provides weary travelers a much-needed escape, but is it worth the expensive entrance fee?See: 10 Airports with Awesome AmenitiesOnce seen as a haven for a privileged few, many lounges are now accessible to those willing to pay a daily use fee. Many travelers receive complimentary access thanks to their elite frequent flier status, or for using certain airline-affiliated credit cards. Lounge fees can range from $20 to 50 per person and typically include Wi-Fi, alcoholic beverages, light snacks, reading material and more comfortable seating than what's available in the terminal. If you're at the airport and are unsure where to go, LoungeBuddy — a free app for iOS and Android — details locations, available amenities, pictures and reviews from other LoungeBuddy users. Lounges operated by foreign carriers tend to be the best, but may be reserved for first-class or business-class passengers. Some include sit-down meal service or individual rooms to catch a nap during long connections. (This is just one more reason to learn how to use frequent flier miles wisely.) Plan your next international first-class award to include visits to Singapore Airlines' Private Room, The Wing by Hong Kong-based Cathay Pacific, or the First Class Terminal operated by Lufthansa in Frankfurt, Germany.Domestic carriers are also rushing to renovate their own lounges as corporate profits improve. You're more likely to find shower facilities, larger snack menus and more plentiful electrical outlets. Domestic airlines don't offer automatic access to their first-class passengers (Alaska Airlines is an exception). But certain elite members of frequent flier programs can request access to domestic lounges if traveling on an international itinerary.See: In-Flight Etiquette: How to Be a Better PassengerAmerican Airlines, United Airlines and Delta Air Lines all work with credit card issuers to provide cards that include membership to airport lounges. With annual fees of $400 to 450 per year, these credit cards are typically less expensive than a lounge membership alone and may come with added benefits, such as complimentary upgrades on award tickets, waived checked bag fee or the opportunity to earn more miles on everyday purchases.Do you travel on many different airlines? Carriers tend to place lounges close to their departure gates, but you do not need to fly on that airline to use its lounge as long as you're willing to buy a membership or day pass. Also, be aware that you can visit a lounge in a terminal other than your departure gate — no special permission is required from the TSA to clear security twice.If you want to avoid feeling tied to one carrier's lounge, you may want to consider the Platinum Card by American Express, which provides access to a variety of lounges. American Express is expanding its own network of Centurion Lounges (currently available at McCarran, LaGuardia and Dallas/Fort Worth airports), which offer premium food and specialty cocktails. Entry to these lounges is free for Platinum Card members or $50 for other Amex cardholders. You can also show your Platinum Card at an Airspace Lounge to enjoy free entry and a food and beverage credit, or request a free Priority Pass Select card to access a variety of other lounges throughout the world.Priority Pass is a separate company that also sells various memberships to individuals who don't have or don't want an American Express card. At the lowest level, it provides discounted access to a variety of lounges on a per-use basis. For those willing to splurge, $399 grants unlimited free visits to the company's entire partner network, including lounges operated by United Airlines that aren't available with Priority Pass Select.Despite the many comforts an airport lounge can offer, there are still plenty of travelers who find no value in its amenities. For the price of a day pass, you might be able to order better food and drinks in a nearby restaurant. Plus, more airports are providing free Internet service to travelers (though the airport-wide Wi-Fi isn't always as speedy as it is in a lounge). And during periods with heavy delays, the lounge can be just as busy — or even busier — than the rest of the airport.But there is one distinctive benefit airline-operated lounges offer: They often have a customer service desk that provides immediate assistance for rebooking flights and resolving other reservation issues. Buying a day pass or purchasing a membership is often preferable to the two-hour wait you'll endure rebooking at the gate. Getting help sooner also means you'll have the best pick of substitute itineraries. Worst-case scenario? You can wait out the delay with a cold drink and comfortable seat.See: How to Book Your Next Award Flight Like a ProAbout the author: Scott Mackenzie is a neuroscientist who learned how to travel and earn elite status on the cheap during graduate school. He now shares these tricks on the blog Travel Codex. You can also follow him on Twitter @Travel_Codex.