Where to start...
MA: Historical: Concord and Lexington (Old North Bridge, Lexington Green, towns themselves), Lowell, MA: Lowell Historical National Park (mill history), Boston: Freedom Trail.
Museums: Too many to list but the Museum of Science for a start.
Fun stuff: Again, so much to list. Cape Cod, Boston (Quincy Market/Faneuil Hall, Duck Boats, Swan Boats), N.E. Aquarium.
ME: Bar Harbor, Acadia National Park, beaches, LL Bean in Freeport, Baxter State Park, all the little coastal towns, antiquing, outlet malls.
Give us an idea of what you like to do-that will help.