Keep in mind, if you fly...
American Airlines - connections in Chicago or Dallas-Ft. Worth
Continental - you will most likely connect in Houston (also, Continental will begin the merger process with United in a few weeks).
Delta - Connections in Atlanta and/or Minneapolis St-Paul, Detroit, or Salt Lake City.
United - connections in Chicago O'Hare or Denver (Again, they will soon start merging with Continental)
Southwest - some flights are non-stop, others have stops and/or connections in the usual SWA cities (Phoenix, Las Vegas)
I saw some references to the "cramped 737" - before you use that as your reasoning to choose, keep in mind other airlines are no different (plus, you will most likely have to navigate a "superhub", somewhere).
My .02
Huh?
Southwest does not fly LAX-MCO non-stop. American, Delta and United, however, do.