[gargamel]

Since everyone is suggesting pizza anyway, you need to stop in New Haven at Frank Pepe's (if you like pepperoni) or Sally's (if you like cheese). New Haven is pretty much the halfway point between Boston and New York, so it will be a nice break and will give you some good pizza to compare to what you'll get at Grimaldi's and/or Difara in Brooklyn. If you're on Wooster Street in New Haven anyway, you might as well walk down the street to Libby's for some Italian pastries while you're there.

If you're in Boston on a weekday, you need to go to Chacarero for a Chilean sandwich. Green beans in a sandwich don't sound good, but the whole combination just works. You also need to go to Kelly's Roast Beef at Revere Beach for a lobster roll. Just make sure you watch out for seagulls because they will steal your sandwich if you aren't careful. That's a lesson I learned the hard way [edit: I forgot that you're going to the Cape. Since you are, Kelly's may not be worth the trip, though it's only about 15 minutes from downtown, so you don't really have much to lose]. Union Oyster House is fairly touristy, but it fairly good and is in a good location for downtown sightseeing, so it's probably worth stopping for a meal if you don't have other plans.