PLimoth Plantation sounds like a great idea. It will be crowded, I imagine. I have never been there on TG, but I have been there more recently than 5th grade, like a couple of years ago.
Here's a tip. It costs just as much for two adult tickets as it does for an Individual+one membership. So, if you go there twice in one year, there's your membership dues. And you'll be helping a non-profit meet one of their goals.