I've been to several of the distilleries. My favorite is Maker's Mark. Another really good one is Buffalo Trace. The Woodford Reserve is near Buffalo Trace and is also pretty good. Mammoth Caves is well worth it and is not too far from Maker's Mark and the Corvette Factory and the Corvette Museum. There used to be factory tours, I don't know if there still is. You'll find that it is difficult to visit more than a couple of distilleries in a day due to driving distances and times of tours. Jack Daniels is made in Tennessee, so is out-of-the-way from just about anything. It is south of Nashville, but that is a good destination also.
http://www.kybourbon.com/english/pages/trail.html
As mentioned before, the Wright-Patterson Air Force Museum at Dayton, Ohio is really good. That had three huge hangars when I was last there and were building another. An absolutely awesome care museum is at Auburn, Indiana. Auburns, Cords and Dusendorf's are displayed there. It is pretty large also. It might be on the way to Niagara after a stop at the Air Force base.
The Louisville Slugger bats are made in Louisville, Kentucky. They have tours that are interesting and relatively short. Worth considering.
Anyways, I really enjoyed the Maker's Mark tour and Buffalo Trace. Both had very good bourbon chocolates.
Enjoy. There's lots to see and very little time.
Dennis Englert