Actually, the 3 oldest, boys 12,10,7 are entertained by Nintendo DS, while the little one, 3 yr old girl, has a portable DVD player to keep her busy. I have lots of Dora, SpongeBob, and she loves Cat in the Hat....Oh yeah!!!
The boys have maps and other things to keep busy as we travel up I-80, and come back I-40. We did this trip before, so it will be fun.
Best thing is a pickup with a camper. Put the screaming rugrats in the camper, and then you can have a nice quiet, enjoyable trip. If the wife's a nag, put her in there with the kids.