Worlds of Fun in Kansas City. I went there dozens of times in my youth, and my wife takes our kids up there several times each summer.
I hadn't been there for ten years until last summer, when my sister & BIL came to town and we decided to take all the kids. I decided to ride my old favorite coaster, the Orient Express, and it was still as good as I remembered. (The other rides, not so much. The Viking Voyage log flume ride is very, very lame.) It's a good thing I rode the Orient Express one last time, because they tore it down last winter after 25 years!
Worlds of Fun was built by Lamar Hunt in the 70s, with a ton of internationally-flavored theming. He sold it to Cedar Fair about ten years ago. Still a nice park, although the theming isn't as rigorous as it used to be. (Why is there a 50s diner next to the Mamba coaster in the "Africa" section of the park???)