You HAVE to stop at South of the Border. It is the most educational place EVER!!
I am totally just kidding. You will be sooooo tired of seeing the billboards for it, you will just be glad to see that huge sombrero in your rearview mirror!
I think Savannah is a great place to stop, especially if you plan on spending at least part of the day touring the city. I think the waterfront is about 30 minutes from 95. Lots of good history for your son.
We have stopped and eaten at Paula Deen's restaurant. It was very good. I know she uses a ton of butter, but it won't hurt for just one meal. The restaurant is called The Lady and Sons. As of 2006, you couldn't make ressies, but they opened the line to make reservations at 3pm for dinner. You had to line up at the restaurant, just to make ressies to come back and eat.
If you plan to do this, call or visit the website ahead of time to make sure this is still the procedure.