In brief, Bright Young Things will be fun for anyone who liked the Luxe books. Vixen, on the other hand, has a pretty cover (although that model's arms look scary-thin) but features some of the most truly cringe-inducing dialogue I've ever read outside of the Sweet Valley High series. (Click through for an example. It's... kind of amazing.)
Book sources: The Godbersen, from my local library; the Larkin, a review copy from the publisher.
Read for the 2011 Historical Fiction Challenge.