On the National Mall starting September 5: End the war, change the world, create world peace, b there or b L7! http://campdemocracy.org/
Well, if your traveling in the fall/winter months I'd suggest the southwest. New Mexico, Arizona, Nevada, Southern California. It's warmer there and it's some pretty country in my opinion. Bustramp
Why do you have to leave... just wonderin.. im floating around of sorts and have been thinking of visiting people in upstateny and maine...
All the other suggestions sound cool. You could also like kinda crash/section hike the Appalachian Trail/Florida Trail for a couple months, some way cool folks, and it is extra beautiful and less buggy this time of year. Plus there's many helpful trail angels along the way, and way easy hitchin'. It would be best to check the weather, probably better down south.
If you go north, the common ground fair is Sep. 23-25 in Unity, maine (pretty organic town), and I could put you up until you figure it out