I don't think I would have Nolan direct or write it but he definitely should be an Executive Producer since Batman is his franchise (unless he decides to severs his ties after he completes his trilogy). As far as Singer, keep him far away.
I have no idea who should write the story but I would definitely bring on board some DC people as consultants if not as writers. (Bruce Timm comes to mind.)
How about the Wachoskis to direct or maybe even Ridley Scott? It needs to be a credible director who has experience with a big production.
Raybia there was a reason why I knew I like you and outside the fact that you have "cooler than cool" Lando Calrissian as your Avatar.

t:
But it the fact that you actually make a reasonable statement to keep Singer away from anything like this and even have them consult with the DC people and you suggest some intereting choices as director.
The Wachooski brothers would proboly be the better choice over Scott because they are fimiliar with the comic resources to make a movie like that.