What's the best recreational facility to bring your child to in or around Yorktown?

There are several different options in the Yorktown area, depending on whether you are thinking of summer or winter, indoor or outdoor recreation.
Jefferson Valley Lanes and Cortlandt Lanes are great for those days you are looking for indoor entertainment. Gran Prix in Mt. Kisco is an indoor Go-Karting option although it is pricey.
In the summer months, the Yorktown swimming pools, three of them, are a great way to keep children occupied. There is a resident pass requirement, although people are allowed to go in as guests of residents also.

Ohh, a wonderful place to bring a child that is sure to delight is Muscoot Farm in the nearby town of Somers. They have walking trails, visitable barnyard animals, hayrides, a museum and a slew of great children's programs. I used to love going there as a little tike! And best of all, admission is free so you can go as much as you like. Its a great way for small children to commune with nature and animals.