Features That Would Make Arkham City a Great Sequel

Batman: Arkham Asylum was one of the most successful games of 2009, with a great storyline, characters, and battle system, it was one of my favorite games ever. But what could make Arkham City as successful as, if not more successful than, Arkham Asylum?

1. Multiplayer has been announced for this game. It seems like a really cool feature, but what I'm worried about is whether this will affect the single player campaign in any way. I don't want developers to concentrate on the multiplayer part of the game since what I really enjoyed was the amazing experience of playing through the campaign.
2. Many gadgets: Although two extra gadgets have been announced for the game, and all the previous gadgets are already there (some improved) I would love to see many more gadgets that make batman what he is.
3. Characters: Bringing back characters from past comics was a great idea, but I would love it if the game included features, whether it's side-missions or something similar to audio logs in Arkham Asylum, that remind us of the character's story during the classic comics.

I'm sure Rocksteady won't disappoint us, but I would sure love it if they included some of these features.And I'm sure you've got your own list of features you would like to see in this game, so go ahead and comment to let me find out!