I'd like to see Oracle, but first as Batgirl. That way, you have the subplot of Barbara--who at first is just imitating her heroes--being broken by the villain, then rising in a way that makes her distinct and awesome. Then, if you introduce a later Batgirl (I would like to see Stephanie Brown personally), there'll be that nagging fear if she too will be broken. It could be really interesting to see play out.
Other than that, more Martha Wayne, and MAYBE Batwoman. Of course, Catwoman is a given already.