Every place we've ever traveled in Maine is gorgeous. We have been to Bar Harbor and all around Acadia. The Park is outstanding. Yes, make sure you check out Thunder Hole and Sands Beach. It would be a shame not to experience sunrise on Mt. Cadillac but be sure to dress for it. It can be bone chilling that time of day.
As someone mentioned, make it a point to stop at a Marden's store. The prices on first quality fabric is better than any place I've ever seen. Don't be mislead by the appearance of the stores; this is how they keep merchandise so affordable.
We usually spend our vacations in the Wells, Maine area on the southern coast. If you get there, you are just a stones throw from the Kittery Outlets and in the other direction, Kennebunkport. Kennebunkport has a quilt shop but have never stopped in. If you get to York Beach, you must check out the beautiful Nubble Lighthouse. Also, right next door to Wells is Ogunquit. There are quaint shops there and theatre if that interests you. Down around the waterfront in Ogunquit is the Marginal Way which is a beautiful, nicely maintained scenic walk that most anyone would be able to do. If you do get around the southern coast, be sure to stop at Knight's Quilt Shop on US 1, north of York and just south of Ogunquit. It is closed on Tuesdays.