My husband and I have been on the New England Cruise 3 times. Love it - Boston, Portland, Halifax - Peggy's cove. Usually take a taxi to Peggy's Cove. We do the bus ride/boat ride in Portland - a tour purchased in town. St. John is neat too - shared taxi with another couple.
Can't tell you much about with youngsters. We did take our adult children and grandchilden on a cruise and they took advantage of kids club to get a break from little ones. It is always fall when we do New England. Should probably have some sun there now. ??? Enjoy!