We did that one a few years ago. Here are some things we liked:
NYC -- pastrami sandwich & cheesecake @ Carnegie Deli and a long walk in Central Park
BOS -- pot roast @ Durgin Park restaurant and a walk around Boston Common & Public Garden
PWM -- lobster @ DiMillo's and a Casco Bay lines excursion to Peaks Island
Halifax -- fish 'n chips and the Maritime Museum of the Atlantic

We went in September, and that year it was too early for the best leaf colors. Hope October works better for you!