If you are passing through Erie, Pa, they have Splash Lagoon there and also Presque Isle. Erie aslo has an outlet mall for shopping. Outside of Niagara Fall, in Grand Island, NY, they have Fantasy Island. It is an amusement park that is geared for younger children. Buffalo also has a zoo, science museum, and Darien Lake (larger amusement park).
If I knew the ages of the kids and the path you were using it might be easier to give some ideas.