Airlines for America, the lobbying group for several major airlines, forecasts 25.3 million passengers will fly on U.S. airlines during the 12 days surrounding the holiday. — If you miss your flight connection — or bad weather causes delays — get in line to speak to a customer service representative. The real secret to the lounges is that the airline staffs them with some of its best — and friendliest — ticket agents. Anything over 50 pounds (40 pounds on some airlines such as Spirit) will generate a hefty overweight surcharge, in addition to the checked bag fee. — Before your bag disappears behind the ticket counter, make sure the airline's tag has your name, flight number and final destination. — Place a copy of your flight itinerary inside your suitcase with your cellphone number and the name of your hotel in case the tag is ripped off. ExpertFlyer.com offers free notifications when a window or aisle seat becomes vacant. Even after checking in, seats can be changed at airport kiosks and on some airlines' mobile applications.