Great Amusement Park!.
Every year when we go back to Buffalo, NY for a visit with family (where we grew up) we take our kids to Fantasy Island. They are both 9 years old and thoroughly enjoy the park. There are tons of things to do both for younger and older kids and for the adults. Plenty of shows and rides. The waterpark is great, too! The price is extremely reasonable compared to others I have been to around the U.S. and, often discounts become available on sites like Groupon or Livingsocial so you get in at half price.
This is the place to go for kids of all ages. No long waits in line. Same great rides but no over crowding, The water park is fabulous. And the wonderful part is you actuallly get to enjoy the rides. Plus it is inexpensive.