My wife, son (25) and I are headed there on the 9th for five days. We're taking in a Red Sox game (Fenway tour earlier that day), taking a harbor cruise and exploring a lot of historic Boston and the Cambridge area (Harvard, MIT, etc).
Then we're hopping over to Cape Cod for a couple of days to watch a few of our Fightin' Texas Aggie baseball players play ball in the Cape Cod league. Good stuff!