The Cranberries are nice. There are free town moorings at both Little and Great Cranberry islands. Little Cranberry is a better place to spend the night (much less rolly and a lot less traffic), but Great Cranberry is more pleasant to walk around on - some nice trails through the woods to pleasant coves, etc.
Somes Sound is a nice day sail when it is a bit cold because it is always warmer than outside the sound. In light air the tide is a factor. The wind in the sound is generally from the north or the south, so figure either on tacking a lot one way or motoring. Valley Cove is an OK anchorage, but the tide swirls through there and the bottom is very rocky so make sure your anchor is set well. Also Valley cove loses the sun early and cools off rapidly. I prefer it as a lunch stop to an overnight. A pleasant day is to run up Somes Sound and back then spend the night over at Little Cranberry. The next day run over to Great Cranberry, pick up a mooring and hike the island.
Northeast Harbor is nice if you like really crowded harbors. Southwest is a lot less crowded and the moorings are cheaper. Unless the wind is from the east, Southwest is very placid at night. The moorings out at Hinckley can also get lively in a northerly stronge than 15 knots, but further in the harbor it will be placid. There are 4-5 town moorings across from the Coast Guard as well as 6 Hinckley moorings on the Manset side about half way up the harbor that are placid unless it blows from the east.
Bar Harbor is a waste of tiome as a stop although it is very pretty to sail by. I prefer to stop in Sorento on the North side of Frenchmans Bay or to make Bar Harbor a day trip from Northeast or Southwest.
The west side of MDI (Blue Hill Bay has lots of interesting places to visit such as Blue Hill, Pretty Marsh, Sawyers Cove, etc.
Swans Island is nice. If you want the city atmosphere try Burntcoat Harbor. If you want solitude there are several nice anchorages in Mackeral Cove on the north side of Swans Island and Buckle Island is also very pleasant.
Frenchboro is also nice to visit. Lunts has very good lobster and lobster rolls. There are also lots of pleasant trails on the island. The harbor tends to fill up early in July and August so you generally need to be there before 2 PM to get a mooring. The cruising guides say you can anchor outside the harbor proper, but the tide runs really hard through there and I wouldn't do it. If Frenchboro is full, then it is only an hour over to Burnt Coat Harbor on Swans Island where there is plenty of room and better protection.
Mount Desert Rock is a nice run from MDI or Frenchboro. Figure on a 40+ mile day for the trip though. I have seen whales one of the three times I have been out there.