Late Friday night at Nobu at the Shore Club – looking "a little disheveled and withdrawn from everyone," a source tells PEOPLE – Wilson dined with a group of buddies before making his way to the Florida Room at Delano, where he met up with an unlikely pal: Sambora.
"Owen and Richie were just chilling together, talking at a table," said an observer.
Meanwhile, Dylan McDermott was just one table away, and eventually joined the two others in their discussion. "They were just being guys, hanging out, friends talking," says the source.
By Saturday, Vaughn had flown into town and joined Wilson for a bit of fun on South Beach, a source tells PEOPLE,
"They hung out at Casa Tua until 5:30 a.m.," says the source. "The restaurant usually closes by 1 a.m., but they kept it open late for Owen and Vince."
As for what took place, "The guys hosted a private party inside and had a blast," the source added.