just commenting on a few things. yes, camp at minuteman cg outside of boston and take the bus into town. Lexington and concord are an easy drive. our first time we drove into boston, horrible. also for dc, take public transportation. the first time we drove in, horrible. do the plimouth plantation. Plymouth rock is cool but you will be surprised how small it is. ranger said that for many years it was carted around in parades at which it would fall off the carts and break pieces off also said tourists would break chunks off as souvenirs.
philly, also do independence hall as long as you are there. not far from the bell.
acadia area, bar harbor cg is good and it is cheap. but there is no ocean access as it is on a high cliff. but good view. bar harbor is pretty crowded so take the free shuttle to get around. we went down to rockland area. nice cgs right on the ocean and not crowded.