When it comes to Zac Posen, no fête is too far, no land too distant, for his loyal gang of international party pals. Especially when the event in question is an all-expenses-paid, festivity-packed trip to Turkey. For that, thank Cem Hakko, CEO of the country's leading fashion retailer, Vakko, which was celebrating its just-launched collaboration with the New York designer. "Who wants an Ambien?" joked fashion publicist Annelise Peterson as the flight for Istanbul got underway from JFK on Thursday afternoon. Ten hours later, rested or not, fellow fliers like Andrew Saffir, Daniel Benedict, Bettina Zilkha, Paz de la Huerta, Nadine Johnson (the PR powerhouse who orchestrated the proceedings), and Padma Lakshmi-Rushdie disembarked, the last to a swarm of local paparazzi. "If I knew they were going to be there, I would have thrown on some concealer," said the model/author/cooking host.

Later that evening, makeup fully applied, the glam group reconvened at Ulus 29. After dining on grilled grouper, roast leg of lamb, and eggplant purée, revelers including Rufus Albemarle, Carlos Souza, and Amy Sacco hit the adjoining club, where they danced until the wee hours to pop tunes spun by model Eve Salvail. "I'm having the time of my life!" said Kate Schelter, the New York consultant who helped broker the deal between Vakko and Posen.

The next morning, even the groggiest guests were primped and primed early (we call 10 a.m. early) for a sail on the Savarona, a six-level yacht with its own salon, movie theater, and library. "When I woke up in the morning, I sounded like I had a sex-change operation," said Houston social force Becca Cason Thrash, whose luggage had also gone missing during her travels. "I called room service for some coffee, and they were, like, 'Okay, sir.'" By mid-morning, she was sipping Champagne on the boat's oversize pillows alongside shipmates Carlos Mota, Douglas Friedman, Bridget Hall, Dita Von Teese, and editrix Isabella Blow, who lived up to her rep for mad millinery in a hat made of feathers that spelled out her surname.

As the giant ship anchored, we snuck off to the Grand Bazaar with the man of the hour and mom Susan for some light shopping. Not surprisingly, it was vintage fabrics and locally made caftans that caught Zac's eye. The former will adorn his sofa at home in New York. "He needs it—he has a wonderfully hideous pink and red couch," said Susan, who ended up paying, after her son discovered that American Express isn't universally accepted.

The final bash of the weekend was a black-tie dinner for 400, elaborately decorated by (yet another New Yorker) Antony Todd at the Les Ottomans hotel. "This morning, this place was empty," said the interior designer of the black and gold, candle-lit space. On a makeshift stage, Dita performed her trademark tease (including a new segment, which featured a giant birdcage that she built herself). She was followed by belly dancers and some wildly popular whirling dervishes—a group of men who spin in long white skirts as part of an ancient form of religious remembrance. Crooner Bryan Ferry marveled at the wonder of it all. "I don't know who invited me here," he said. "But I'm glad that they did."