We were just up there in June. Near freeport we stayed at Cedar Haven Family Campground, nice campground, nothing special but nothing bad about it either. Freeport has outlet stores and it has LL Bean which is a pretty neat set of stores to look through. Harraseeket Lunch and Lobster had the best lobster I have ever eaten, the price was very reasonable too. Lobster orders are taken at the back serving window, there is a side window for other food orders. Right on the pier.
On Mount Desert Isle we stayed at the KOA just as you get onto the island several years ago (we didn’t go to the Island this year) it was a good place to camp, right on the water and convenient to Bar Harbor, Acadia and to Ellsworth.
Maine Maritime Museum near Bath is a very good stop for a day. Nice displays inside and out.
We went up and stayed in Harrington ME, Sunset Point Campground. A small, simple campground with not much more than an office, bath house, laundry, and some walking paths along the water. there is not a lot to do near there, it was just a couple of lazy days relaxing. We drove up to Lubec to see the large tides the area has.
US1 s a pretty drive, but it can be pretty crowded and slow in places. If you go north of Ellsworth the traffic clears up pretty quickly. We drove I95 up to freeport then US1 from there up to Harrington.
If you don’t have an EZ-Pass I suggest you get one before you go up that way, lots of toll roads.