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That sounds like a great trip. I'm not sure if the trip is too ambitious, although I think you might be better off leaving off Boston from this trip. It's quite a long distance from the other spots you mentioned, and even without it, you've already got 7 things you want to see and do in your 9 days - most of which really will take most of a day.

For Philly, make sure you make an online reservation to tour Independence Hall,, it's free to visit, but you can only see it on a tour, and they book up very very early if you go in person.