Plymouth Village, I think that is the name of it, is well worth the visit in Mass. Best lobster I have had was at Newport Tennis Club in Newport R I. They play croquet at the "tennis club". The tour of the mansions in Newport is nice too. If you doit be sure to take one that has the Vanderbuilt "summer cottage" in it. Jackie O's is the least impressive. I have never been to Boston but I am sure there is plenty to see there. I grew up in D C so can suggest any place is good to see. I would take a bus tour of any of the cities as it is less hassle and you do not have to worry about getting lost, finding a parking place etc. And the guides on the buses are full of info. Also you might consider taking a walker that has a seat for your mother. I always take mine when I know I will do a lot of walking. Have a fun and safe trip. Take care.
Linda