MaidMarian...not sure where you live, but STL is one of our airports...we live in southern Illinois. For us STL is 2 1/2 hours drive almost, Nashville TN is 3 1/2, Louisville KY, Bloomington IL and Indianapolis IN are each right at 4 hours so I check them all as well as Evansville IN, which is 2 hours, but isn't as big of an airport so fewer options. Of all the airports I've mentioned STL tends to be the most expensive and since we end up staying the night before and after flights I usually go with the cheapest airport, which for our December 18 - 25 trip was Nashville. Originally I got BNA - MCO on SWA for $111 one way before all the taxes, fees and such. However on Friday, I got a DING fare for Nashville for $35 one way and it was for the exact same flights, so I saved a bundle by cancelling and rebooking.
So, my point is if you can fly out of another airport, you might want to look into it. Also, have you checked into the MidAmerica Airport which is on the Illinois side, near Scott Air Force Base? I see signs near there for $79 oneway to Orlando...just don't know anything about the service.
Hope this helps!