I am currently on a different road trip and as we were traveling I was looking through some tourist things and discovered two more baseball themed things to work into next summer's All the Ballparks road trip.
The first is the Indiana Baseball Hall of Fame and nearby League Stadium, where they filmed A League of Their Own. This is a little out of the way to add to the trip, but somehow we will work it in. Perhaps make it a really long day trip out of Cincinnati to the Lousiville Slugger Museum and here or maybe head to Indiana from Cincinnati and then spend a night in Lousiville see the Slugger Museum and continue back on planned route.
The second is the Pujols Westfront Grill in St. Louis. Now this is an easy thing to work in or at least it should be considering it is a place to eat and in it in a city already on the route.