I'd recommend you get and read Anthony Bailey's The Coast of Summer
. The book describes a summer cruise along much the same areas as you're talking—LI Sound, Narragansett Bay, Buzzards Bay and the Islands—but in the opposite direction. He was in a Tartan 27 IIRC. It describes many of the anchorages and ports of call quite nicely and is an excellent read besides. However, a week would be a bit short in terms of time, depending on what you're planning on seeing.
As for the other direction, a week would definitely be too short. If you go up the Cape Cod Canal, you could cruise the Boston Harbor Islands and then do Cape Ann, but I think, given the size of your boat and average speed, that a cruise to Maine would also require far more time. Some places to stop on the way through Cape Cod Bay, Boston Harbor and Massachusetts Bay include:
Onset, Plymouth, Provincetown, Scituate or Green Harbor, the Boston Harbor Islands
, Great Misery Island, Marblehead, Salem, Gloucester, and Rockport.
You could also circumnavigate Cape Ann, and come back down the Annisquam River, instead of reversing track.
Another thread to read is this one