T.G.
We have 4 kids and have been driving back home at least once a year since they were infants. Our car trip is 21 hours and 2 days. I have learned some tricks over the years.
1) Invest in a portable DVD player that straps to the back of the drivers seat. They can play your childs favorite movie or music CD.
2) Crayola makes markers that only color on special paper. This and a lap tray work wonders.
3) Sit in the seat next to your child is a good idea and makes it easier to tend to them without pulling the car over.
4) If they are awake, stop every 1 1/2 hours for about 10 minutes and let them run, run, run . . .. . play tag for a minute if you have to. It helps them to work of energy.
5) Have a small cooler with sippy cups of milk, juice and healthy snacks
And most important, don't forget the Motrin in case your child does not do well with long car rides!!
Good luck and have fun!!