I haven't noticed anything on the big stage in my recent trips. Margaritaville often has someone playing inside and a guitar player/singer on the porch, Pat O'Brien's has the dueling pianos, we have seen live music at Antojitos, there may be others I can't think of.
Check the Hard Rock Live event calendar. One year we walked up and got great tickets for a Twisted Sister Christmas show. Have also attended several comedy shows during some of our stays.