There is also a legal seafoods airside in Terminal B, so could have something to eat in B and than take shuttle over to C. I would take the shuttle if you have luggage, otherwise walking will be a good workout. Your not in a hurry so either option will work. Another great thing to do if you exit security is to go to the top of the central parking and look at the skyline across to Boston. Take a photo or two from the top level.

Cheers.