My favorite is Castine. So much history, signs everywhere walking around the town. I love their little sheltered beach - Wadsworth cove beach (even though it's not quite sand, it's not all rocks so that's a win in Northern Maine). Not sure about shops or food, I only go there as a day trip. It's just a nice chill town to visit and you don't feel mobbed by tourists because it's not just off a major road.