As I've posted on here before, dh and I prefer to drive just about anywhere with the kids. Every time we fly, we run into delays and cancelled flights. In other words, flying with the kids is a nightmare. Thus, when we take the kids to WDW, we drive; when it's just dh and me, we fly. It doesn't save us any money with gas prices the way they are, but it does save our sanity.
For us, it's a 15 hour trip...if we make only a few brief stops. I prefer to leave home in the late afternoon or early evening. Driving through the night means that we avoid all traffic. The roads are pretty much empty (We even drive through the heart of Atlanta.) until we reach Orlando the next morning. Our 3 children (13, 5, and 3) watch movies until the fall asleep, usually around midnight. They will sleep until we wake them the next morning. Yes, we're tired when we arrived but never so tired that we can't put in a day at the parks. It's no worse than flying, since we have to leave our house by 2 am at the LATEST to make the morning flight to Orlando. I don't know about you, but I'm not able to sleep when I know I'm leaving for WDW in just a few hours!!