We just returned from driving to WDW. We left on a Tues. afternoon at 1:00 -- wanted to leave earlier but kids had some tests to take before leaving -- drove until 7:00 -- stopped 1 hr. for dinner and then drove till about 11:00 -- we stayed over in Florence, S.C. Left 8:30 a.m. on Wed. a.m., stopped in Augusta, GA for 1/2 hour for lunch and then arrived at OKW at 3:00 p.m.
Ride down was great -- ride home seemed a lot longer. We stayed in Disney till 1:00 p.m. (had planned to leave by 11:00, but weather was so great, we couldn't get motivated), had hoped to drive till 11:00, but only made it till 9:00 and kids were tired. Stayed again in Florence and then drove home to Philly following day.
I HATE to fly, so don't mind the drive. We've taken the AutoTrain in the past, and have found that enjoyable also. The kids liked the car ride better because they could watch DVDs and play Game Cube, on the AutoTrain you don't have easy access to outlets. The plus in taking the train is you arrive in Sanford at 8:30 (if you're on time).
The drive is as good as you make it. With a positive attitude, it can be a fun trip!