If Southwest flies in and out of an airport that's reasonably close to you, they're your best option. This is (apparently) the only airline that doesn't charge ANYthing extra for cancelling or changing tickets - although if you rebook on a higher-priced flight, obviously you have to pay the difference. One drawback is that they don't release fares more than a few months in advance; another is that they don't have assigned seating. When you check in, you get boarding passes marked A, B or C. This indicates with which group you board, and then you just get on the plane and pick your own seats.