I also enjoyed the witch museum in Salem.
We did a bit of the freedom trail, but ran out of time (spending most of it on the Constitution, so I don't regret a minute of it). We visited the House of Seven Gables as part of the walk, it didn't appeal to me much because I had never read the book. I wished I'd have seen Bunker Hill.
So in short, all I saw was the Constitution, and I loved it.