I'm a little biased but I think it's the pinnacle of sailing Maine. Turn your engine off and follow the windjammers for a few days. Thread your way through the islands.

As Steve said, Boothbay is a convenient stop between Penobscot and Casco. That leg south from Penobscot Bay to Boston may be tempered by southerly winds so leave some time for it. On the other hand, you might get sailing conditions that make you want to push right on through.