Ashley and Mary-Kate Olsen
06/02/2009 AT 06:00 AM EDT
and Ashley Olsen
, enjoying dinner and dancing together at Lavo, inside the Palazzo Las Vegas. After celebrating a friend's birthday with a meal in the private dining room, the twins headed upstairs to the club, where they snagged a table on the dancefloor. "They danced non-stop with their friends and playfully took photos of each other," says an onlooker, noting that the twins stayed until after 3 a.m. "They loved the music the deejay was spinning."
After a rowdy night
at the MTV Movie Awards, Cameron Diaz
kept the party going at Teddy's inside the Hollywood Roosevelt Hotel,
where she sipped white wine and chatted up Hayden Panettiere
and Zachary Quinto
. Later, the trio was joined by Zac Efron
and Vanessa Hudgens
, who were wrapped up in each other. "[They] were holding hands, dancing close and always had their arms around each other," says a guest.
After a dinner at Nobu West Hollywood, Brody Jenner
, Frankie Delgado
and JC Chasez
also made the Teddy's party scene. Jenner and his wingman met up with many of his Hills
castmates (including Lo Bosworth
, who was getting down on the dancefloor) and stuck by the bar most of the night.
and fiancée Jenna Dewan
hung out at West Hollywood's Chateau Marmont, enjoying a casual evening tucked away at a back table on the patio. When the action star's G.I. Joe: The Rise of Cobra
costar Sienna Miller
arrived, Tatum went over to greet her. The two laughed hysterically and seemed happy to catch up, but soon Tatum returned to his fiancé and resumed his quiet date night.
New mom Rebecca Romijn
, getting glam at the Byron & Tracey Lounge in Beverly Hills. Romijn – looking natural sans makeup in black pants and a white T-shirt over a bright orange tank – was all smiles as she nibbled on mini sandwiches while getting her hair trimmed at the salon's VIP Lounge event. She also headed to an outdoor gifting suite and picked up some goodies, including unisex sunglasses from Carerra.
and boyfriend Mark Cornelsen
, enjoying spa treatments at the Spa Gaucin at the St. Regis Monarch Beach Resort in Dana Point, Calif. The Grey's Anatomy
star received an hour-long therapeutic massage. By ALEXIS CHIU and JENNIFER GARCIA
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