For those of you still planning your summer vacation, I very enthusiastically recommend that you give Ogunquit a shot - I honestly think it's just the most perfect summer town ever, and has something for everyone (carnivals, antiquing, gorgeous beaches, great food, fishing, et cetera). It's pretty busy on summer weekends, but if you can steal away during the week you'll find better prices on hotel rooms and shorter lines at restaurants.
A few of my favorite area must-dos: