Though they reunited for a family bowling outing in November, on Monday, it was all business for Courteney Cox and David Arquette as they lunched together with three associates at Morton's the Steakhouse in Burbank. They arrived and left separately, though Arquette kissed his estranged wife on the cheek when she entered the restaurant. "They were very cordial and friendly," an onlooker tells PEOPLE.

Meanwhile, in L.A., Zac Efron and his girlfriend Vanessa Hudgens feted the actress's father on his birthday at Morton's the Steakhouse in Bubank, Calif. The group shared lots of laughs over their dinner, which ended with a birthday cake and a "Happy Birthday" serenade. According to a source, "the group couldn't have been nicer."