Thanks for bringing the awesome weather with you from CA! Can't add too much to the previous posts other than NYC is only 3 hours away.
Freedom Trail is fun, the ancient cemeteries are the best part.
Nice Restaurants:
Troquet: very spendy French
Red Lantern: excellent Asian fusion
Stephanie's on Newbury
Chez Henri in Cambridge: Cuban French, excellent
Great smaller, "local" places
Jose's: great, divey hole in the wall Mexican in Cambridge
Mr. Bartley's Burgers in Harvard Square
Kelly's Roast Beef, multiple locations...these are awesome sandwiches
Redbone's BBQ...just get the beef ribs. You have to go here for lunch or dinner before you leave
Go to the HOTC tomorrow, grab a sausage off a cart and watch the boats go by.