I think that Kingsisle should update their arenas, by adding arenas for the newer worlds like: Wysteria, Wintertusk, Zafaria, and Celestia. Also I think subscribers (or maybe even crowns players) should be able to hear the arena's specific battle music, not the repetitive Wizard City theme. For example, the Drangonspyre arena should have Dragonspyre battle music.
Anyways, I hope you enjoyed my ideas and maybe Kingsisle will follow through with this.