Lancaster Pennsylvania = Dutch Wonder Land for the younger kids. Hershy Park for the teens. And Amish town.
Manhattan = Bike riding in Central Park. Ice skating in Chelsea Piers (or if you will be in Brooklyn there is Aviator Sport Center). A whole bunch of Museums to chose from. Toys R Us in Time Square.
Horse back riding in Jmaica Bay or Prospect Park.
Conserts – there are a few, but i dont know details.
I hope this helps! ENJOY!!!!