I've flown AirTran out of Philly three times now and have had great experiences each time. I love the convenience of being able to choose seats and print boarding passes from home. The service has always been good. Prices are usually lower and planes are no less comfortable than USAirways, who I used to fly exclusively and with whom I have become disenchanted. I really feel like their virtual monopoly of the Phila. airport has kept prices sky high here as compared with other comparable airports (ie Baltimore). I'm tired of it. I hope with Southwest coming in (they still are, aren't they?), things will start changing for the better.
Anyway, sorry for my OT ramblings. I would recommend AirTran without reservation.