New Hampshire to Yellowstone

Thanks to all who replied. I'm definitely going to take a few of the suggestions especially dropping by Niagara Falls. One of the conundrums I have is not being able to stop an extra day here or there if you find an interesting place because the reservations lock you in to being at a certain place on a certain day. I'm thinking of only making reservations in the busiest places like Custer S.P. Yellowstone, Niagara Falls etc and taking my chances that I'll find a spot to camp otherwise along my route. I'd like to get your thoughts on that. When we headed out in 2010 we never planned more than 2 days out and never had a problem. We traveled through most of the Eastto Tennessee then the South and Southwest.