My 3 kids are pros at long distance trips. We've become very blase' about 10-24 hour drives. My kids are 4, 8, and 10, and are good travelers, but it's not because it comes naturally to them. We bought a TV/VCR which made all the difference. We also take personal tape players with books on tape (Lady and the Tramp, Harry Potter), and we have 2 GBA's and a Pixter. We don't let the kids have the GBA's unless we're in the car 30 min or more, and they rarely get to play with them at home, so they are a real treat. The GBA's belong to my dh and me, and the games are property of the boys. I keep all of it stashed in my room to insure it doesn't get lost or broken.
When we moved from Minneapolis to the border of TX & LA, my girlfriend filled a big shopping bag with wrapped gifts. It had candy, toys, activity books, snacks, and a CD. The kids really looked forward to opening a package. What we've found really works for us is to make sure we have a video they haven't seen. On day 2 of driving we stop at a
WalMart and let each pick out an inexpensive toy as long as they're not fighting and doing as they are told. Also on day 2 we try to find a fast food place with an indoor playland. They get to run and play all they want then get food and eat it on the road. While they play we eat and relax as much as you can in a playland. We had to drive between MN and TX 3 times in 3 months, so we have no fear of driving to Orlando.
No matter what the weather is, each kid has a pillow and a small blanket. You want to start a fight? Just make 2 kids share a blanket...it won't matter if it's king size, it just won't be big enough. On that note, when we forgot the stack of blankets, we bought beach towels at a WalMart. They do double duty nicely.
This next trip we'll leave about 4 PM and drive until probably midnight. That way the kids are tired enough to settle down right away. Our first choice is to nap in the early evening while they are allowed to stay up and play then get up about 2 or 3 a.m. The best, quietest, most sedate hours of the trip are until they start coming to life around 8 a.m.