Living it up in Sin City, the original "Girls Next Door" starlets were spotted out for a book launch at the Forum Shops in the Caesars Palace Hotel and Casino on Saturday evening (December 20).

With Kendra Wilkinson (who showed off her engagement ring), Holly Madison and Bridget Marquardt all on hand, the three lovely ladies smiled as they posed for pictures and greeted fans - trying to build up sales during the holiday shopping season.

The previous night, all three of the Playboy babes were busy celebrating Holly and her new boyfriend Criss Angel's joint birthday party at LAX Nightclub.

While there, Criss told People magazine of his season's wishes, "I don't want anything for Christmas. I just want Holly, love, health and happiness, and I have all of those things."

Giving back the love, Miss Madison turned to her magician beau, saying, "I just want you. I'm in love and I'm so happy."

Gossip Girls

Enjoy the pictures of Kendra Wilkinson, Holly Madison and Bridget Marquardt in Vegas (December 20).