Keep in mind that your child(ren) will be in "holiday" mode. They will be easily over-excited, so it will be your job to keep them focused on things that will keep them grounded. When traveling with my children, I always pre-wrapped little travel surprises to keep them busy and focused on the "now." When they first got in the car (or on the plane), they would open their first surprise - a travel game they could play together.
After 1/2 hour (more than enough "together" time), they would receive another surprise - crayons/markers and paper. Another surprise could be a small chalkboard and chalk - even though they're still drawing, a different medium makes it a completely new activity! Continue with this every 30-60 minutes, using small items that can be played with quietly. ALWAYS give the next surprise before they have a chance to start whining - you don't want to reward the whining!
To prevent any antsy behavior, play "follow the leader" at each rest stop. Be sure to include stretches, some aerobic activity, some more stretches, then some relaxing breathing once they're back in the car. After you've led the first one, the kids will do a great job of leading during the rest of the stops - and they'll love it!
By Connie from Erie, CO