Well first off, on the Cape you will find Cape Cod Beer in Hyannis. They are in the middle of expanding, so not sure what their tour schedule is or if the self-guided tour will be available, but they will definitely let you taste and pints are also now available there. Their porter is excellent and their current have a new beer Biere De Mars on tap, a French Farmhouse ale. I have not tried, but it sounds good.
There is Cisco based on Nantucket. Their beers are available on the Cape and most of MA. Anything in their Island Reserve Series is worth trying, ditto with their "The Woods" series. Also Mayflower Brewing in Plymouth, their Porter is also excellent and their Spring Hop Ale is now out.
Those are just three local breweries in the area you will be visiting. Someone with more expertise can give you specific beers in MA not in PA. But if you go to seekabrew.com and select MA and then select your state to compare it with, the left column result are beers not in your state. Doing that myself, a few stick out. Boulevard, their beers are excellent especially Tank 7. Jack's Abby, Idle Hands, Clown Shoes, Element, Rising Tide and Full Sail are other producers of some very good beer.
Also, if you are in the Boston area, you need to go to Cambridge (right across the Charles River from Boston) to Cambridge Brewing Company, the most popular brewpub in area. They produce a great deal of good beer!
Hope that gives you a starting point!