Back to back parties
When you book a hotel here, you need to ask around. Sometimes staying one more day can turn up a lot more fun.
In the summer time, sure- there's the big Thunder On the Ohio thing, but that's just one of dozens of Riverside-Drive-closing activites. There are barbecue cookoffs and always some sort of convention going on.
In short, once you're set, ask a native. The Convention and Visitor's bureau will also have most of these listed.