We only made it into Kentucky for 2 days; just to visit Mammoth Cave National Park. (It happened to be National Park Week, so our tour was free!** Yeehaw!)
It was my first visit into a cave and it was far more fascinating than I anticipated. Our guide was excellent, which probably helped, and I loved the stories he told. I didn't realize it would be so cold...not so fun for the kids. But I really loved learning about the various people who had explored the cave thousands of years ago. And how items people brought into the cave were preserved for that long: the minerals, air, temperature, etc. created a perfect environment so things didn't decay.
And we had to have breakfast at the Waffle House at least once...a Southern icon. And, yes, Simon did eat the butter...
**It should be noted that we never paid to get into a National Park our entire trip. We didn't plan it this way and kept thinking we should just buy the $80 pass that gets you into all the National Parks. But we just got fortunate that the ones we decided to go to didn't charge. Did you know that 268 of the 401 National Parks (historical sites, parkways, etc.) are always free? Pretty cool!