Who parties with a beautiful woman on each arm? Ryan Reynolds, of course! Olivia Wilde and Leslie Mann flanked the actor at a party celebrating his new Details magazine cover Los Angeles last night. Over in New York, Whitney Port caught up with former boss Diane von Furstenberg at a CFDA Awards after-party, where Ashley Greene talked fashion with her designer date Michael Kors. Click "See the Photos" for shots of Alexander Wang, Gerard Butler, Carey Mulligan and more stars at last night's hottest parties!