You have to stop in Washington D.C. Beside the monuments, there are great museums you can visit. I would also go to Orlando/Miami. Just driving around is a great sight!
If you make your way to Milwaukee at all let me know and we'll hit a bar or something!
The Sprecher Brewer (not sure how well they are known outside of the states, inside they are mostly known for their rootbeer) does a tour complete with 4 free samples of their wonderful beer
I would recommend stopping in Chicago. And get Chicago style Pizza. It is THE BEST type of pizza there is. And if you want a real eye opener... stop in Detroit.