Here are a few photos from last night.
Nicole attended Christina Aguilera's party at Tao restaurant and nightclub in Las Vegas.
Miss Richie hosted a New Year's Eve party at Lavo.
She looked gorgeous in a gold mini dress covered with paillettes, a custom piece from her collection Winter Kate, and her Yves Saint Laurent pumps.
Nicole and her friend Jennifer Michelsen head back to Los Angeles in their private jet