As a Mainer, I'd recommend the following for summer on the coast: hit Yarmouth for the Clam Festival by the 15th of July, then Freeport with LL Bean and the Harraseeket Lobster Shack, then move up to Christmas Cove, for classic coastal scenery, then visit Rockland, for museums and galleries, then Rockport or Camden for shops and windjammers. All of this means traveling on Rte One or 95. Just avoid Wiscasset during Friday nights or Sunday afternoons-- miserable traffic. Farther north, don't miss Acadia Nat'l Park, and the elite but lovely towns of Northeast/Southwest harbor.