We have been to many of these places but in three or four trips.Here are some helpful thoughts. If you get a late start and want to stop along the Ohio Turnpike several of the rest areas have RV hook ups. Also think about stopping in Shanksville PA. at the 9/11 site. Gettysburg visitor center is a great place to start your tour. Cherry Hill is the place to stay while in DC. We have taken the bus from the campground to the Metro station. It takes you passed the University of Maryland and down side streets. It is faster to drive to the Greenbelt station and if a weekend I think you can park for free. The Metro is the way to get around in DC. There are many places to go in DC and most are free.Not sure if it's still this way but some tours had to be set up through your Congressman's office.
NYC we camped at Liberty Harbor in NJ and walked to the PATH station and took it into the city. They also have a ferry boat that takes commuters across the river to NYC.
Don't over do it and try to cram to much into one trip. Your making memories not enemies when children are over tired and grumpy
