I'd Second Winter Island in Salem Ma. It's no Normandy Farms, but being right by Salem Harbor, and the beach with tidal pools was lots of fun for our girls. We drove to Boston MA but could have taken the ferry. Girls loved checking out stuff in Salem
Here's some pictures and about the area.
Winter IslandStop by Mystic Connecticut on your way up -
Mystic AreaOh- and Peters Pond was nice on Cape Cod.