Just got back, and thought I might reply to my own thread for those who might be in the same situation. This is by no means a comprehensive list, just observations from our 8 days around the area:
The highlights for my daughters (ages 3 and 6) were the (free) Samoset mooring in Rockland which included use of their facilities (Pool and playground most importantly), The numerous kid appealing stores in Camden, Northeast Harbor on Mount Desert Island (the gardens at the top of the hill were a great place for them to run around), the country store 1/2 mile walk from Pulpit harbor with great ice cream and owners kids who share their toys, and at the Northern End of Somes Sound, there is a campground with a swimming dock and lots of small kids.....