Leaving baby Luca at home, Hilary Duff and husband Mike Comrie enjoyed a night out at Surrender Nightclub in Encore at Wynn Las Vegas over the weekend. The pair, situated in the VIP area near the DJ booth, joined friends as they listened to DJ Tiësto and Manufactured Superstars during the club's two-year anniversary celebration.

Duff "seemed very excited to be out with friends" and was "in a great mood," an onlooker tells PEOPLE. "There was lots of laughing and smiling." Nearby, Benicio del Toro (also a new parent) and actor Lukas Haas partied in another VIP booth.
– Melody Chiu and Jennifer Garcia

Nicole Richie stepped out for a girls' night out in Las Vegas. Heading to XS Nightclub along with five pals, the Fashion Star judge headed to the Wynn Las Vegas's nightspot to dance to tunes spun by deejay duo Manufactured Superstars.

Richie, who recently bared her bikini body in Miami, and her pals took over the owner's table before jumping up on stage for a bit where she was (obviously) spotted by clubgoers. Richie was dressed to impress, decked out in rocked a salmon blazer worn over a black and white-printed blouse.

It's a classic case of the rich getting richer.

During her birthday weekend in Sin City, Paris Hilton cashed in to the tune of $30,000 while playing blackjack at Wynn Las Vegas.

Hilton Tweeted about the big win, writing" "#BirthdayGirlsLuck. I love gambling."

On Saturday Hilton, who turned 31 on Friday, continued the birthday celebration at XS Nightclub with sister Nicky Hilton and her parents.

Also along for the party: Hilton's rumored boyfriend, Afrojack, who played deejay at the bash. Donning a silver cocktail dress, Hilton partied at her table inside the club, but continually went to the outdoor deejay booth where Afrojack was spinning.

She later added via Twitter that the night was "EPIC."