03/09/2009 at 02:20 PM EDT
A "gorgeous-looking" Gwen Stefani
, stepping out for dinner with her family – her parents and sons Kingston, 2, and 6-month-old Zuma – at Hugo's in Sherman Oaks, Calif. "Kingston was running around the place having fun," says an onlooker. "Gwen kept having to run after him but she was totally cool about it. She was so sweet and calm and collected."
, treating the crowd at West Hollywood gay bar Here Lounge to an a cappella performance of her song "Poker Face." The stylish singer – in a short white jacket and dark miniskirt – walked right up to the deejay booth, asked him to turn down the music and then belted out the chorus and a stanza from her new single. There for promoter Tom Whitman's weekly "Size" party, the pop star surveyed the scene, had some drinks and posed for pictures with clubgoers. Later, Katy Perry
made a brief appearance, stopping in for a beer and saying hello to Lady GaGa.
and Justin Gaston
, getting "talkative" over sushi and tea in the main dining room of Nobu West Hollywood.
, sipping on margaritas over dinner with Joe Francis
and a group of women at L.A.'s Velvet Margarita. The guys ate enchiladas and "looked like they were having a blast," a restaurant patron tells us.
Neil Patrick Harris
and Christina Hendricks
, joking with friends and fans at Bardot Hollywood. The Mad Men
star sipped a Joan Holloway cocktail and raved to her server about her television character inspiring its name. "I never thought I'd ever have a drink named after me," she said.
By JENNIFER GARCIA, LISA INGRASSIA and KRISTEN MASCIA
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