I enjoyed their Southern music audio tour which was small, but informative, and got a kick out of their comic book exhibition which focuses on Southern Stereotypes like King of the Hill and Snuffy Smith (two of my favorite cartoon/comics to begin with).
Don't spend a ton of time in the permanent exhibit all about Charlotte since it will eat up a good chunk of your time. The highlights are the parts where you can touch cotton in its various forms, listen to and watch interviews with the original demonstrators in the luncheonette counter sit-ins, and read sticky notes posted by school children addressing issues from industrialization to racial equality.
Reading the sticky notes was highly (and I DO mean highly) engaging, though usually riddled with the sad state of affairs that results from a lack of grammar correction. I liked the interactive aspect of it - almost akin to allowing kids to write on the walls or tag the art. And truly the luncheonette counter footage gave me chills.