V.N.
I think it just depends on your children. My son (27 months) hates sitting still in the car. We just drove 4 hours Monday and for the amount he wasn't sleeping he was asking to get out of the car seat. In September we drove to Florida and it was a sixteen hour drive. We ended up leaving 5 in the evening and got there in the morning. It was hard to drive overnight but I knew that my son would not last.
It appears that everyone down below has great ideas as well. Have a great holiday!