Have you looked at this thread:
Marriott Bonvoy hotels in or near Boston, MA
Number 4 on your list is new, but not close to Boston per se. Good transit connections, but it isn't Boston. At least with your Cambridge options you can *see* Boston from there.
Of the two Cambridge options, I think the Meridien is located in a better (less busy) area.
You don't want a car in Boston or Cambridge. Transit is easy and nearby. Parking is expensive and traffic is bad.
I agree for a family, a R.I. might make more sense.