I'll throw my two cents in for southern Indiana (don't be discouraged if you've only seen the flat areas of the state).

Brown County State Park in Nashville has great camping, trails, mountain biking, etc. It's located in the middle of some of the states best little wineries and the city of Nashville has a mini-Pigon Forge or Gatlinburg feel to it (emphasis on mini)

There is slow river tubing/canoeing available at Turkey Run state park to the west, on the White River to the north as well as some other areas to the south.

I'd say start by checking out the this link and go from there and go from there. Of course you can PM me if you have any other questions.