We just drove down for the first time ever last week, and I have to admit it was a really easy and pleasant drive, and plus we had our much more comfortable car while at WDW, rather than a rental. With plane tickets out of Des Moines over $900 each during spring break (limited capacity coupled with only legacy carriers makes this a tough place during peak times), we figured it was worth a shot, and it went very smoothly. The children slept in their car/booster seats while I drove through the night, and during the daytime portion they watched Disney movies on the car's DVD player. Outside of one minor traffic snag south of Atlanta, we sailed along very nicely.
The part that made the overnight drive really tolerable, however, was that I listed to Podcasts for about ten straight hours, each way, and they kept me entertained and engaged and therefore alert during the overnight portion of the drives. It was my first time listening to them, and I must admit that I am now completely hooked and will become a regular listener. They streamed very nicely over the phone into the car's radio, and I didn't have to play radio-station roulette all night.