Ashton Kutcher

The right coast to party on this weekend was the east coast. Star have flocked to the Big Apple for Fashion Week. And the parties never seem to end for the rich and famous, who were out in full force in all areas of Manhattan.

On Friday night, Rag & Bone designers celebrated fashion week with a party at SL (Simyone Lounge), Eugene Remm and Mark Birnbaum's newest New York ultra-lounge, not yet open to the public, in the fashionable Meatpacking District. Among those mingling with fashionistas in the crowd were Rob Buckley, Avril Lavigne, Nicky Hilton, Shannon Elizabeth, Jessica Stam and New York Knicks' David Lee.

Designer Charlotte Ronson celebrated fashion week Friday night with family including, DJ Mark Ronson, Annabelle Dexter-Jones and DJ Samantha Ronson, who was behind the turntables, as well as friends including Kirsten Dunst, Nicky Hilton, Avril Lavigne, Amanda Bynes, Andy Samberg, Tinsley Mortimer and Erin Lucas at Abe & Arthur's Restaurant on 14th St. in NYC.

Partygoers sipped on specialty Svedka Vodka cocktails like the Hot_Bot and were treated to a sneak peek at Style Savvy for Nintendo DS.

Ashton Kutcher Demi Moore, as well as Mischa Barton, Molly Sims, Gerard Butler, Sara Paxton, Corbin Bleu, Nico Tortorella, Benjamin Hollingsworth, Mark Lacono, Lo Bosworth and Amanda Bynes celebrated the CW premiere of The Beautiful Life at SL (Simyone Lounge) in NYC's Meatpacking District on Saturday night.

The same night, Menu Suvari, AnnaLynne McCord, Ashley Greene, Nicky Hilton, Kristen Cavallari, Jared Leto, Lindsay Lohan, Stephanie Pratt, Shenae Grimes, Jill Zarin, Kelly Bensimon, Tinsley Motimer and Fabiola Beracasa, among others, joined alice + olivia for a fashion show and concert by all-girl Parisian quartet, the Plasticisines, while guests enjoyed specialty Svedka Vodka cocktails.

Model Noemie Lenoir celebrated her birthday with an intimate dinner at Abe & Arthur's Restaurant while owners Eugene Remm and Mark Birnbaum dined with Gerard Butler. Later that night Sean Penn was seen stopping by with his girlfriend Jessica White.

Amanda Bynes, Nicky Hilton and old friend Brandon Davis made an appearance at designer Adam Lippes' after-party at 1Oak. Lindsay Lohan made a surprise appearance at Tenjune Nightclub Sunday night.

On Monday night, 1OAK was the place to be yet again. The club hosted an after-party for the MTV VMAs, which also celebrated the release of Jay Z's new album, The Blueprint 3. Justin Timberlake, Rihanna, Jessica Alba, Diddy, Kim Kardashian, Jude Law, Michelle Trachtenberg, Gerard Butler, Mickey Rourke, Whitney Port, Kimora Lee, Djimon Hounsou, Ne-Yo, Stephen Dorff, Nikki Hilton, Cassie and model Alessandra Ambrosio, among others, joined Jay Z and club-owners Richie Akiva and Scott Sartiano at the party, which went on until the wee hours of the morning.

Celebs sipped on DeLeon tequila and champagne while listening to tracks off HOVA's new record as sparklers filled the room. The party topped off the weekend for the hip-hop superstar, who kicked if off with his sold out 9/11 benefit concert, "Answer the Call," at Madison Square Garden on Friday night.

It may sounds crazy, but remember…celebs never stop, and NYC is the city that never sleeps!