We've done it from DFW and had a blast. We took the city bus from the airport to the beach and hung out all day. If I recall, it wasn't a terribly long bus ride (maybe, 30 minutes?)...and we had a great time.

This was before 9/11; so, we didn't stress about getting back to the airport more than 30 minutes before our flight. And, we had trouble getting on the direct flight and had tom come home through IAH...but, all in all, it was a great day and totally worth it.

Good luck!

Lisa