I don't have any suggestions but I may take some of yours
My kids will be 5 and 3 (almost 4) when we drive down. Our garmin says 16 hours and yahoo driving says almost 18

Probably will be somewhere in the middle but honestly we are going to drive as long as possible the first day (barring any weather we are hoping to make it 14 hours and if we really could do 16 to get there we'd probably try to do the whole thing). Lofty goals with two small kids but dh is going to come home from work, load the car, and go to bed. Then we plan to get up at 1ish and get the kids in the car to head out while they are still sleeping and the traffic is much lighter. Then in the morning dh will sleep while I drive. We have a dvd player in the car, we'll bring card games, coloring books, toys, etc. Anything we can think of that will entertain them. We will also have the small potty and food. All I need is to get caught in traffic when one of the kids (namely ds) has to go to the bathroom. We'll need the potty I guarantee it.
How long is your drive?