I remember doing a thread a while back that had all the main players in the Batman mythos casted with their ideal film counterparts. For the part of Catwoman, it seems unanimous on here since I originally picked Kate Beckinsale as well. Must be the fact that she's a more than capable actress who looks REALLY good in tight black leather!
As for Rosario Dawson, she may even be a better choice for Det. Montoya (for those who don't already know, she was the character who was usually paired up with Harvey Bullock when going on duty). She certainly has the look and the presence for the role.
