If you hunt Hotwire.com "hot rates" you might snag a Boston waterfront hotel (Harbor Hotel) or other 4-5 star (InterContinental, Meridien, other) for $200-$300/nite in Boston. If that's the level of "luxury" you're contemplating. Same for Portsmouth, Portland and mid-sized harbor towns.
Fellow Maine Adaptive volunteer owns Pilgrims Inn on Deer Isle, ME. He and his wife are terrific hosts and the food is a fantastic.
http://www.pilgrimsinn.com
Acadia is a special place. So many options ...