Blake Lively managed to fly under the radar – not even getting photographed – during a private, four-song concert by pal Florence Welch and her band, Florence + the Machine. Lively and the musician were attached at the hip after the Belvedere-sponsored performance at the Boom Boom Room atop New York's Standard Hotel, sharing drinks (think: martinis!) and lots of laughter. Also at the bash: Kanye West and Emma Roberts, who was surrounded by girlfriends. – Jessica Wedemeyer

After her revealing night at the CFDA Awards, Lady Gaga was ready to party. The Icon Award winner and close pals headed to the Top of the Standard at New York's Standard Hotel for a star-studded V magazine fete that drew out revelers like Gerard Butler, Kirsten Dunst and more. Guests sipped Belvedere cocktails named after Gaga songs, and enjoyed a surprise performance by Patti LaBelle, who serenaded the crowd with "Over the Rainbow" as Gaga joined in at the end of the tune.

Rocker John Mayer encouraged several ladies to put down their glasses of sparkling wine and take tequila shots with him during a bash at the Boom Boom Room inside N.Y.'s Standard Hotel following a Cinema Society screening of Happythankyoumoreplease. But the talk of the party was a leather-clad Ed Westwick, also in a leather cap, who worked the room and spent some time talking to Billy Joel's ex-wife Katie Lee outside the VIP lounge.

Kelly Osbourne jumped into a hot tub fully clothed and bounced a beach ball with her male friends (who were just wearing underwear) while partying at Le Bain inside New York's Standard Hotel. The starlet was there earlier to celebrate at the V magazine bash at the Boom Boom Room, also at the Standard. Meanwhile, Mary-Kate Olsen was dancing nearby and strolling the room in a leopard-print jumpsuit.