Mr. Bills Thrills in Troy, MO has been open in previous years, but no official announcement of them being open for this year. Same for Greg Allen's haunt Fear Fest and Necropolis which were both in Columbus, MO (I believe).
Obviously The Darkness will be open and the Insane Shane party will be going on as well. Otherwise there's usually tons of people out and about the town doing dinner and hanging out at bars all weekend. There's definitely not a short supply of things to do!