Are you interested in biking by any chance? If so, Brewster to Provincetown is a nice ride. When you get back to Brewster, you could have dinner at chillingsworth (I assume it still exists). Sandy Neck is also kind of cool (sand dunes). And, how about Osterville?

I will ask my mom for other tips next time I talk with her. She has lived on the Cape for 45 years, and knows the lay of the land.