If you are into Lighthouses there is a ton of them. Llbeans original store is in Yarmouth and is open 24X7. Camden is also a great area. I second the rest of your itinerary. For me Campobello was outstanding. Eastport another picturesque Village is across the bay, well worth your time.
Delray

And now that my life is so prearranged
I know that it's time for a cool change