Chad Kimball, Jessica Biel, Justin Timberlake and David Bryan
05/05/2010 at 05:00 PM EDT
and Jessica Biel
had a date night at the Tony-nominated
at New York's Shubert Theater. At intermission, the happy couple ventured backstage to meet the cast – plus Bon Jovi's David Bryan
(who wrote the music and lyrics). "Justin kept his hand on Jessica's back the whole time," a show insider says. "Justin couldn't stop raving about the show and how it really hit home [since] he's from Memphis."
After performing at
the Met's Costume Institute Gala in N.Y., Lady Gaga
kept the party going at New York's Royalton Hotel, where the pop diva danced the night away. Joined by pals like Justin Tranter from Semi Precious Weapons (the band is opening for the singer's Monster Ball tour), Gaga spent time in the deejay booth with Lady Starlight and also held court at a table full of fashionistas.
Meanwhile in Las Vegas, Joel Madden
deejayed from his table at Moon Nightclub. The Good Charlotte singer was joined by friends at the club's weekly Bang! party, where he sipped vodka and Red Bull as he spun tunes. Earlier, Madden dined on lemon chicken and creamed corn at N9NE Steakhouse inside the Palms Casino Resort.
, taking shots and acting "very single"
at the weekly Bolthouse Tuesday Nights party at West Hollywood's Trousdale Lounge, an onlooker says. The heiress, who was joined by sister Nicky
and Brandon Davis
, showed off her dance moves and gave various male clubgoers kisses on the cheek before leaving to find another party.
By JENNIFER GARCIA, MARK GRAY and LESLEY MESSERRihanna Parties in Berlin Until 5 a.m.! >