Id love if they added a guardian library that you visit in a special sector of the tower. It'd be cool to read all the grimoire you collected in game. It'd be neat if there were a bunch of warlocks there walking around and studying. Be a good idea to have social spaces that only certain classes could visit inside of the tower. Wether it be traveling to a place that's right beside the tower from the destinations tab in-game or just requiring a class to walk into a sector of the tower.