I couldn't agree more with the previous recommendation for using Chowhounds as a food resource. I use it all the time...both here at home in Los Angeles and when I travel.

Also, since you are driving for part of the way try looking at Road Food http://www.roadfood.com This is the website of a couple that travels the highways and backroads of America, trying out places to eat. There is also a book, and they write for Gourmet magazine. You'll find some fun suggestions, and probably some real authentic old-style American cuisine!

Have a wonderful time. Natalie in Los Angeles