I have a plan for you. I would recommend that you stay in only one hotel. One that is located on the T (Subway) and is fairly convenient to all things Boston. Free Parking is key. Easy access is too. Try not to drive in Boston when you do not have to. If you are close enough in town the T, taxis and Uber are not that expensive. I recommend the Hampton Inn Boston/Cambridge.
You can drive to Tufts quite conveniently. Otherwise, I would recommend public transport for the other schools. All except for WPI which you could visit on the morning of your departure before your drive back to New Jersey.
What do you think?