Can't really help answer your question, but, my wife and I just came back for the Ark Experience. You'll love it. Prepare to go early and spend most of the day there.
Hit some caverns on the trip, Mammoth Cave, etc.
Do a tour of one of the stallion farms in Lexington (Jonabell or Claiborne). If the kids have seen the movie, Secretariat, he was buried at Claiborne.
The Buffalo Trace distillery is actually really awesome with lots of history and is educational. I suppose it would depend on the kids ages.
I hope this helps.