The U.S. economy has been battered, but luxury and optimism live in Las Vegas. The $9 billion CityCenter project, which is a joint venture between MGM Mirage and Dubai World that includes hotels, gaming and condominiums along with retail, has upped the luxe ante, signing a roster that includes Ermenegildo Zegna, Louis Vuitton, Tiffany & Co., de Grisogono, H.Stern, Marni, Rolex, Mikkimoto, Roberto Coin and Tourbillon.