When I lived in Boston, I often travelled to New York for the day. Took an early morning shuttle flight, then bus from the airport to Grand Central Station, which in itself is worth a visit! Then I'd walk to my appointment with plenty of time to stop at places like the FAO Schwartz store, the Steuben Glass Museum, the Met. The point is, as has been pointed out, it is a very walkable city. Oh, there's St. Patrick's Cathedral, Saks, the NY Public Library, Rockefeller Center. Enjoy yourself.