Jen Klein's 'Day of Indulgence'

The scene was the Brentwood home of film producer Jennifer Klein. The occasion? Her annual girl’s-only "Day of Indulgence," attended by a veritable Who’s Who of hip Hollywood: Rebecca Romijn palling around with fellow model/actress Tyra Banks, Michelle Trachtenberg scoping out the earrings, and Katie Holmes buying for baby Suri. "I got a lot of dresses," said Holmes. "I got a diaper cover, I got a jacket and a new hoodie for her."

-Reporting by Rhonda Richford

It was a gorgeous California Sunday, and the rooms of Klein’s house were filled with clothes, jewelry, and cosmetics—all on sale at a discount. Besides the numerous “pamper stations”—offering massages, manicures, pedicures and even eyebrow waxing to restore any guests worn down by all the shopping and socializing—there was an abundance of fortifying food. "We're going to head over to the chocolate now, definitely," Holmes said. "I've been looking at it for a while now from over here."

"Last year was my first time, and now I don't want to miss it," Messing said of the event. "When I came, I didn't even know about the goody bag, and it barely fit in my car! I just heard that it was a lovely afternoon where everyone puts on summer dresses and celebrates the summer. And you know, my birthday is on Tuesday, so it's a nice way to do an early celebration."

"I think Jennifer brings the right amount of girls," said Beauvais-Nilon. "And I think it's nice that you can't bring someone, because that way you get to mingle with people that you wouldn't talk to otherwise."

"It's really fun to be here with friends and to just shop and have all of these great vendors here, and it's nice to be with everyone and talk to everybody," said Holmes, who chose a vintage floral-print dress for her first Day of Indulgence outing. "It felt very summery."

"I don't really do anything when I'm here," said Banks. "I just like to walk around and talk to everyone. I can't do a mani-pedi or something where I'm stationary. I just want to see everything and eat and talk, so it's hard for me to actually relax, because I'm having such an exciting time."

"What I love about the food is that it's not chichi poo-poo food," said Tyra Banks. "It's, like, real—fried chicken, potato salad, summer barbecue food." Indeed, Mary Pat Brandmeyer Catering kept the picnic theme going with lime cilantro salad, tuna-fish sandwiches, French fries and Caesar-salad cups.

"I had so much fun!" Cross said. "I got a manicure, a little shopping, a little socializing—sort of like a perfect Sunday afternoon."

"I got this fantastic pair of earrings," said Kristen Bell. "They're very similar to the ones Michelle (Trachtenberg) got. I saw Michelle's and I said, 'I have to see if there are any left.'”

"This is the place where I get to see Rebecca every year, but this time we made plans to hang out in a couple of days! I'm excited—we've been model friends since back in the day," said Banks. Added Romijn: "I gather all my most important information for the year here at this party. Makeup, food—all of it. And products. Seriously, it's important information that you get. It's very informational. It's practically academic—with no books, though."

"Jen Klein is one of my favorite, favorite people. I mean, outside of this day she's an extraordinary woman, and she puts her heart and soul into all her projects," said Trachtenberg. "But this day is so much fun because you get to see all the ladies you don't get to see, and you get to do a little shopping. And who doesn't bond sweating it out in the sun, sipping on an iced tea and trying on dresses?"

The desserts on offer were literally the icing on the cake: chocolate lava and chocolate-chip cookies, mini chocolate tarts, and peach and apple turnovers from City Bakery; mint, orange, chocolate, vanilla, lemon and peanut-butter cupcakes from SusieCakes. Before she left, Katie Holmes asked Jen if she could take some of the cupcakes home. Jen sent her off with a box of four.

"We love the gift bag!" said Tyra Banks. "Jennifer is one of my best friends in the world. But I still do love the gift bag. I come for Jennifer but leave with the bag, so it's 90% Jennifer, 10% gift bag."

For more InStyle.com coverage of the party, click here.