Southwest is AWESOME!!! we fly into TF Green on SW everytime we go home to my parents house (on Cape Cod). They don't charge for luggage....it's just no frills. I've never had a bad experience. I never understood the whole thing w/ SW and thought it was weird that you don't book your seat assignment in advance, but my boss talked us into trying it. (and the prices can't be beat over Delta and the other big ones). We don't get Jet Blue or Air Tran out of our airport, so SW is the cheapest.
We made sure we checked in 24 hrs in advance to get a good boarding pass letter ( the earlier you check in, the better chance of an A / B boarding pass which means you'll get first choice of seats). Now, apparently, SW is part of resort check in at most or all Disney hotels so you won't have to pay $10 early bird check in to get a good boarding letter...you can do it from your phone or your hotel.
All in all, I would choose SW first over any other airline. We're checking prices on the website daily for our Sept flight...I don't want to fly any other airline. I don't think you'll be sorry choosing them.....they're wonderful and their staff is also very wonderful.