We did it a couple of years ago, and it was a well spent 3 days.
Louisville is a great town, if you can stay at the Seelbach Hilton, do so. Great hotel, right in downtown, close to a couple of distilleries as well as the Louisville Slugger museum. Check out the ceiling art in the basement hall.
We spent a nice day at Churchill Downs, if it is racing season, it's worth a stop.
The distilleries were all great. Surprisingly, Beam was the one we enjoyed the most, but all of them were welcoming and kinda fun. Gotta agree with dipping your own Makers bottle. Pretty cool.
For some unknown reason, there are several good Cuban restaurants in and around Louisville. Hit up Havana Rumba for a nice meal.
Make sure you get your passport beforehand and stop by the Visitors Bureau in Louisville after you have all the stamps. Collect your t-shirt and go home happy after learning about bourbon and probably finding a new favorite.