Chernobyl, that was a place I've always wanted to see and was always fascinated by. But other than that, I'd love to visit the deep deep ocean, it scares me but I'm so fascinated by it. All those creatures and fauna, things we've yet to discover. Good stuff.
And as for a simpler place, just the bottom of a fresh waterfall, ah to wade in the cool water and to hear the waterfall fall into the water below...it's absolutely stunning.
Definitely Japan, Costa Rica, and China. I took Chinese as a minor in college and classes in high school. I'd love to really immerse myself in the language and culture there.