Welcome to the RTA Forum!

A good rule of thumb is that you can cover about 500 miles on a comfortably long day on the road. Now, you wouldn't want to do that every day of your trip, I don't imagine, but that does give you some idea about how much ground you can cover.

Sticking with that, pretty much anywhere east of the Mississippi would be pretty easily. You could also reach out to the eastern edge of the Rockies, say Colorado or the Black Hills and Badlands of South Dakota.

You could possibly push onward to places like Yosemite, Utah, or maybe the Grand Canyon, but that's going to start putting you into a position where you are doing long days of driving almost every day of your trip.