A couple of suggestions, based on my own memories of trips in the 1980s:
Have you thought of renting an RV (recreational vehicle) -- a "motorhome"? They are very well appointed, the RV parks are superb, and the cost is probably very reasonable.
We went through upstate New York, crossed Lake Champlain by ferry to Burlington, and on through Vermont and Massachusetts. Fantastic places, scenery, wildlife, open and welcoming.
You probably weren't thinking of going off-shore, but whale-watching is brilliant in New England. We went from Gloucester, Mass; expertly organized (we got close to big and little whales), and they're probably even better these days.