Tarrytown and Westchester has a ton of stuff to do. Check out some of the suggestions on TTHE.
You can check out shows that are currently playing and purchase tickets direct from the shows page, TodayTix, or TDF sites around the city.
There are a number hike, bike, and walking trail around the area and on the otherside of the Hudson. Some of our favorite trails are Bear Mountain, Anthony Nose, Breakneck Ridge... Check out the AllTrails app for more options.
Go shopping for any last minute items at the Palisades Center mall.