I'm sure it's further away than you are looking for, but I suggest at some point you go to Mammoth Cave. The hiking is nice, but you won't find anything as pretty as in your pictures. The caverns, however, are an absolute natural wonder that everyone should see at least once in their lives.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell
