If you walk the Freedom Trail, I think at the end you can get a water ferry ride back to near the beginning. Paul Revere house is on the trail.
Museum of Fine Arts
DeCordova Museum is a little outside of Boston.
Walden Pond, same vicinity as DeCordova Museum.
Also Minuteman National Park.
Maybe a whale watch ride?
If you plan ahead, maybe catch a Blue Man Group show.
Don't know if Lord Stanley Cup will be around then.
There's Fireworks & Boston Pops & howitzer/cannon/1812 Overture at the Esplanade if you are actually here on 7/4. Enjoy crowds?
I am taking that week off as well. PM me to exchange cell #s, maybe we can do dinner one evening. I'm 20-25 west, 30-40 minutes depending on traffic.
Or if you're heading west, can have lunch at Wayside Inn in east Marlborough, stop see my fencing club and collection of wirewrapped fencing machines with epxressPCB-made LED boards.
You-do-it Electronics in Needham - will seem overpriced compared to dipmicro tho.
If we have any surplus electronics supply outside of computer places, I don't know about them.
Drive 4 hours out - you can be in Albany, NY! Its not that big a state.
Can drive out to Provincetown on the end of the cape. Stop in Hyannis for lunch.
Down to RI and catch a ferry out to Nantucket or Martha's Vineyard (have not done myself, only flew out in my plane on a nice day).
4 hrs north can put you well up on NH or Maine as well, get some fresh Maine lobster
Get a map and a compass, draw an arc 50 miles, 100 miles, you can be a lot of places in 2 hours (depending on where you are staying & rush hour traffic).
You know that 1-eyed glass blowing guy that's on PBS often? I think he has a display going on now too.
There's no straight roads here, make sure you have a GPS with an up to date map!
Durgin Park in Fanuel Hall has good seafood too. And there's several microbreweries in the same area.