I haven't enjoyed a tour this much in years. Our guide Nicholas has tremendous knowledge and experience in all aspects of horse racing (history, breeding, training, etc.) because he is highly involved in the sport himself. Perhaps most importantly he knows the local horse farms and their owners very well. His family has lived in the Lexington area for 5 generations and it shows in his comments and observations. Also, he encourages questions and does his best to please everyone on the tour.
We visited Keeneland where he took us to the owners' box and every other element of the track. We visited the grave of Seattle Slew and went to a "retirement" venue where we were allowed to feed several Triple Crown winners and the horse who played Seabiscuit in the movie. The horses, stables, and barns on the numerous horse farms we passed were magnificent and Nicholas knew the stories of all the owners.
Even if you are not a huge racing fan (and I am not), I would encourage you to make reservations for this experience.