You could spend the entire day doing brewery tours (not recommended before the wedding, but feel free to knock yourself out on Friday or Sunday), but if you have to go to only one brewery while in Cincinnati, we recommend you check out Rhinegeist!
Still a functioning Amtrak train station, the Cincinnati Museum Center houses not one, not two, but THREE different museums! See the of Museum of Natural History and Science, Cincinnati History Museum, or the Children's Museum, or see all three - just don't miss our wedding (hahaha)
While you will all get to see the Cincinnati Art Museum since it is the venue for the wedding, we will note the wedding starts at 5 pm on Sat AFTER the museum is closed to the public; so, to truly see and enjoy our favorite spot in Cincinnati consider visiting at another point during your trip. Best of all - it's free!