We have found that the drive to WDW is about 12 hours driving time for us. For my daughter, this turns out to be a "three-movie trip." We thought about driving through the night last trip, or trying to book at room about halfway along the route and split the trip up. That didn't work out - I didn't get home from work until around 7 that friday night, and was really too tired and keyed up after a long week at work to even want to try make the trip that night. Besides, trying to find a room at the last minute meant that all the rooms were more than we really wanted to spend.
Strangely enough, this all worked out for the best. We got up and out by 5 am the next morning, and with good driving were in our room, checked-in, unpacked, and had supper by nine o'clock local time that night.
Some tips that have helped us :
1. The tv/vcr, of course.
2. Take rest stops often.
3. For us - have a gps ! It's not that we need it for the route, we
know that by heart. My wife found this it was much easier for
her to drive a longer stretch if she knows how far it is to the
next major stop/turn/city. In addition, I plot out where the
highway construction may be, so as to possibly avoid it.
4. The cooler.
5. A set of toiletries just for trips, for all of us.
6. Before packing, we cover the seat and floor with an old
blanket. This makes it a snap to clean up any messes.
7. A box with medicines - headache, motion sickness, etc.
I hope this helps.