Here are some options for families- Caramoor in Katonah has the Dancing at Dusk concerts which are geared towards kids. The lawn is open for picnicing- I hope to go next time because it looks like fun. In the southern part of the county, New Roc City has mini-golf, Funfuzion Games and Rides, and Applebees and Buffalo Wild Wings, which are both pretty kid-friendly.
There are an absolute abundance of fantastic night spots, depending of course, on your mood and your entertainment preferences. For a lively bar scene, head on over to the Mamaroneck Avenue strip in White Plains For an evening of fine theatre, grab tickets to a Broadway style show replete with a decent dinner at Elmsford's Westchester Broadway Theatre or catch a dance troupe like Ailey II at the Emelin Theatre for the Performing Arts in Mamaroneck. For live music aficianados, there is the incomparable Tarrytown Music Hall in Tarrytown, NY or even The Bayou in Mount Vernon with its authentic Cajun cuisine and amazing blues and Zydeco acts almost nightly. There are also a dozen great cinemas in the area which show everything from fine arts flicks to the big Hollywood blockbusters. Try the Jacob Burns Film Center in Pleasantville or the cushy seated Cinema de Luxe in downtown White Plains.