Yeah depending on how much time you are going to take and what you really want to see you could realistically spend time in all of the New England states in a week. The driving distance between all of them is so short. When I loved in CT we made the drive to Kittery Maine in about 4 hours. We were on a long weekend and managed to do MA, VT, ME, and of course CT that weekend. Granted we didn't spend a lot of time in each state and having more time would have been outstanding but it does go to show how easy it is to drive between the states.
(for reference it takes about five hours to drive all the way across Iowa...lol...really the states are close in NE!