Clearly the Riddler should be David Tennant:
The thing is, because of the insane buzz this one will get, they don't need to blow their load with massive names to fill these roles IMO.
I see no problems with Catwomen either, that totally fits with Nolan's vision, it's the Villians with actual OTT powers that I would imagine he'd stay away from, Poison Ivy, Bane etc.
As for who should be Catwomen, I'll go with Kate Beckinsale