I checked SW and Delta and am going with Delta. they were cheaper, plus the seats are pre-assigned which means no rat race for the best seats. also, they get me into Orlando earlier in the day, and bring me back later in the evening which means more park time on the first and last day.
Have you all tried Jet Blue? I fly from NY to Orlando for under $100 (in feb, DS and I each paid $69!), and the customer service is great, plus unlimited snacks/drinks and a DirecTV in each head rest with free ear phones.
I've flown JetBlue and really like them, but I have to go to Boston for the flight. Limo service to Boston from my house is about $100/each way (for 4 people) which adds another $50/pp. MHT is less than 15 min from my house and I can easily get a ride for free. I don't fly out of Boston unless I can save at least $100/pp on my flights as it isn't worth it for me, or if its an international flight.
Jet Blue does offer great fares! Unfortunately if I wanted to use them for my Nashville-Orlando flight, I would have to "connect" through NEW YORK!! LOL.