Rockland is a great spot to do that. So is Camden. It's one of the few places you can get all your boat needs(diesel, water, ice, pump out) as well as full provisions, and more, within a couple hundred yards of your dinghy or sailboat(with free dockage for a couple of hours). No schlepping.
Stoningtons grocery in the harbor was going full tilt this season, so that's a convenient stop for provisions, for now...
There are not too many convenient places between WesternPenbay and MDI for fuel or general boat needs. It's a good area to practice your sailing and anchoring.