Southwest and USAirways are the only two airlines that operate that route with nonstop flights. Other airlines can fly you too but with one connection somewhere. Because Southwest offers one way fares, USAirways normally does the same. It's probably way too soon to book that trip if you're traveling next summer. Keep in mind that Southwest does not charge for luggage....2 pieces per person free whereas USAirways and the others do charge extra and that can add up to a lot of money.
BobK/Orlando