Agree with other posters that the Cape can be stunning in winter. My favorite place in the National Seashore is Great Island in Wellfleet, miles of beaches, dunes, woods, and quietude. Also stunning are the high dunes of Provincetown around the Race Point Visitors Center.
Best winter birding in the state, other than eagles at Quabbin, is Plum Island on the North Shore.
And just to add one: Right outside Boston is the Blue Hills Reservation. Great Blue Hill, all of 600 feet high, has a spectacular view of Boston, the Boston Harbor Islands, and the surrounding region. Half-hour hike from the parking lots to the summit. Also on the summit are two great stone towers, one to climb for the views and the other housing the oldest continuously operating weather station in America.