Westchester County Airport, 240 Airport Road, White Plains (New York), +1 914 995-4860 (airlines), . The closest airport, about 35 minutes drive. Rental cars are available. By bus, take the #12 to White Plains for the #14 or #15. 
Stewart International Airport, 1180 First St, New Windsor, +1 845 564-2100, . Another alternative to the congestion of the 3 major airports, but at present offers few direct flights. A little further than Westchester County Airport, but closer than the 3 New York City area internationals.
Newark Liberty International Airport, Newark, New Jersey, , John F. Kennedy International Airport, and LaGuardia Airport: The three major international airports in the New York City area offer service to just about anywhere. Westchester-based taxi and livery cars offer regular service to and from the three internationals from most areas of the county. New York City yellow cabs will take to you Westchester in a pinch, but the fares can be exorbitant. If staying in Westchester, ask if your hotel offers shuttle service.
There is a station on the Metro North system in Peekskill, with service to Grand Central Station, from which the 3 main NYC airports can be reached by public transportation or taxi. 
Ride the mountain bike trails at Blue Mountain Reservation, Welcher Ave, +1 914 862-5275, . Parking fee on the weekend. Helmet required, trail map is available online or at Blue Mountain Reservation office. Seven miles of trails in 1,600 acre county park. Trails are marked for level of experience.
Take in a show at the Paramount Center for the Arts, 1008 Brown St, +1 914 739-2333, . Features stage productions, live performances of music and dance, classic films and recent major releases, and visual arts exhibitions.