FYI...
We are going to be traveling to NC with our 10 month old daughter next month and I know we will want to stop often to get her out of the car seat and let her release some energy.
I was planning to manually figure out all the McDonald's along the way that have a playland (since she isn't yet walking fully I figured that would be better for her than a rest stop area).
I found that McDonald's provides a nice utility to let you map out your trip and find the McDonald's along the way with playlands, wireless, etc.
http://www.mcdonalds.com/usa/rest_locator.html
That was much easier than I thought it would be!