I think Clemence Poesy (Fleur from Harry Potter)would be a good Tanya
I heard Kristen Bell may play Kate
And that either Blake Lively or Jessica Stam is playing Irina
Jessica Alba is supposed to be playing Carmen
Elazar is supposed to be played by Brandon Beemer and Garret is supposed to be played by Zachary Quinto
I think they all look pretty good for the part but all the girls are like blonde! I can't remember if they were in the books but ah well.