Boy, that inn looked great.
We like to be near Portland because that's where my husband's mother lives so it's easy to visit from there. For ease, I'd fly into the airport in Portland and go north. A convertable would be great. I'm with Mermaid, NO hitch-hiking, SJ!
Around Portland you have:
The old Port area on the Portland harbor (nice shops, restaurants, bar, upscale but not stuffy atmosphere).
Beaches -- Crescent Beach is one I remember but it's not the only one
Also consider visiting some of the islands. There's Peak's Island right off of Portland. Then Monhegan Island I think is a bit north.
I also like the towns of York and Kennebunkport (The Bush family's compound) near Portland.
I think Popham Beach is about 2 hours or so north.
Rockport and Camden are a bit farther.
I didn't go farther north than that, but I've heard northern Maine is awesome. Of course, the farther north you go, the less crowded it will be.
Look at VRBO for Maine Coast and you'll see some nice places come up and get some ideas about what goes on in these areas. I think places along the coast book up pretty quickly. You want to be sure there's really a beach nearby if you like the beach because Maine coast can mean a rocky coast (beautiful, but not for swimming).