We have always driven everywhere and we travel quite extensively, I don't fly, period. Been there enough, done that and refuse to do it again. (I guess an emergency would change that)
Started when my oldest was 6 months and he's now 24 and my "baby" is graduating next week. Several long trips each year.
Here's some ideas. To DisneyWorld we traveled from WI, which I don't think is too much different than your trip.
1. Took "prize bags",(they even liked them as teen-agers!!!), but by then it was a "tradition". They got one every "so many" miles, or "so many" hours. Usually depended on how many prizes I had and how many miles we had to go. These included anything a little more expensive like hand held games I'd get on sale, even the little ones are good for this, funny candy things, (you can find goofy lollipops, or stupid candy things, little car games, (popular one was car sized Simon), baseball or football cards, (a pack every so many miles), the traditional can't forget, "Pez Container", and then another prize would be a package of Pez Candies. Last year we took my niece and nephew on a trip and her favorite was a set of paper dolls, (magnetic), that she could color the way she wanted, activity books. Well, you get the idea, I would start keeping my eyes open for several weeks before and keep my stash. I'd put one prize in a plastic lunchbag with their name on it.
2.Always ate at rest areas to let the kids run around. Always had a cooler. One of the favorites was Lunchables. We found that eating lots of candies made you sick by the end of the day and a light lunch was perfect.
3. Left early, 6:00 to 6:30, by noon you've really got a good start usually and feel you've accomplished a chunk.
4. Stopped about 5 to 6 at a motel with a pool. Kids had a swim, we had a really nice dinner somewhere, a little TV and they'd be rested and ready to go in the morning. And so were we. We found driving straight through made us sick when we got there and unable to enjoy the day.
5.TV with video was wonderful. Can buy adapters that fit into the cigarette lighter.
6. When you get into Florida a little ways, there's a Walt Disney World station where Mickey and friends tell you what's going on at Disney World and then a stop at the Ocala
Disney Store really starts getting you in the mood.
Well, even if you fly this time, maybe this well help in the future. Have fun!!!