I love to fly ATA out of Indy to Florida. I take a flight that leaves Indy at 7 or 8a and I am in the parks by 11. The return flight gets me home to Indy around 10p. Both flights are nonstop.
Last I checked (for Nov 31 to Dec 5) it was $169 RT.
I went to Expedia.com last night and found a flight for my dates for $111 and a couple for $125. If you go to Expedia and click on flights then click on "Fare Calendar" it will show you the cheapest flights and when they are offered. Southwest, however, is not listed and last time I looked ATA wasn't either, though they always have been in the past.
I think I am going to stick with the ATA flights (433 and 438) because they are the fastest, the times work best for me, and the flights have always been on time (knock on wood) and that is worth the extra $$ for me.