8 Day NE Trip itinerary help

I apologize for adding yet one more post asking for help regarding an itinerary but here goes. We are a family of 4 (set of parents and two daughters - 20 yr old and 25yr old) planning an 8 day trip middle to end of May. Flying in to Boston and doing a loop to Bar Harbor and back. We would like to spend a day or two in Boston on the front or back end. We have spent little time in New England (one Thanksgiving in Falmouth about 10 yrs ago where we explored the Cape ). We are looking for a trip to enjoy the quintessential New England experience - cute towns, good local food, pretty walks/hikes, local shops, local history etc. My initial thought is something along the lines of Boston - Kennebunkport - Portsmouth- Bar Habor - Boston. Would love any and all thoughts on this itinerary as well as specific recommendations in and around each area. Thank you!!