My husband and I share your interests and the trip we will be making to the east coast in late May/early June will cover it all (Art, Music, Architecture, history, natural wonders, solitude).
Frisco, CO to Chicago to Toronto (Yo Yo Ma is performing with the Toronto Symphony) to Montreal to Quebec City (by cruise boat from Montreal) south through Vermont on the east side of Lake Champlain to Holliston, MA (SW of Boston) to Ireland.
Naturally we won't be sailing our motorhome to Ireland. We're leaving it with my son to use for the summer and then he will drive it back to Colorado with his family.
We've driven cross-country numerous times to New England. Each time we take a different route. Every one of our journeys has been a memorable one. If traveling to Montreal interests you I would suggest returning to Chicago via upstate New York and south of the lakes. One memorable campground north of Cooperstown is a very peaceful KOA nestled among Amish farms. We followed buggies going into town when we went to the baseball museum. You could also take a short side trip to Niagara Falls on the return. Lots of campgrounds in that area.
Congratulations on 25 years of marriage and happy traveling.