Audrina Patridge and Lauren Conrad by Chris Polk/MTV Audrina Patridge and Lauren Conrad by Chris Polk/MTV

At a private hilltop location in Los Angeles, The Hills cast and their fans on Monday celebrated the Season 3 finale with a blow-out party that featured a performance by Usher, a screening of the season closer and cocktails on a lawn with sweeping views of the city. Despite the unusually chilly temps, the stars turned out in their hottest threads, including frocks from Lauren's line for her and Lo. The conspicuous absences of Heidi and Spencer (rumored to be sequestered elsewhere) were the big buzz, but the cast stayed mum on why the pair didn't show.

While The Hills cast has seen its share of drama, there's only more to be had in Season 4, especially as these twentysomethings get more serious about careers, relationships and, of course, feuds. As Lauren, Lo, Audrina and others arrived on the scene, TVGuide.com caught up with them to get a preview of next season. Here's what they had to say about:

Boys and Relationships:
For Season 4, expect more, more, more. Lo and Lauren throw a big party in their new pad and invite boys galore. The ever-single Stephanie feasts her eyes on, well, everyone, and Lauren may have a new beau in tow. And as for Audrina and Justin Bobby? They're definitely back on, but as for how hot things will get, Audrina would only say, "[Justin has] always been there for me, and he still is."

Drama and Frenemies:
Don't hold your breath for a Lauren-Heidi relationship thaw. Despite Heidi's ostensible good-will appearance at Goa, Lauren says she "will probably not" reconcile with Heidi. Ever. And as for the growing tension among Audrina, Lauren and Lo, it's just a part of growing up. Audrina says she knows her new focus on her career has meant that she's not around as much for Lauren. Add Justin to the picture, and you've got a recipe for friendship dissolution.

For Lo's part, she sees the tension as having nothing to do with her, despite her self-described "foul face" when the topic comes up. Next season, expect more from Lo's perspective. "It's disheartening to see me turn into such a bad guy on the show," she said. In Season 4, she promised, "You're going to see the other side of the story. I think people need to remember that it's Audrina and Lauren's relationship that's having problems.... It's not my relationship to muck up."

Careers and the Future:
With Lauren officially working side-by-side again with Whitney, will there be a turf war at People's Revolution? Whitney says no. "I don't like to be alone," she confided. "I'm used to having lots of girls around me all the time, so it's great to have [Lauren] around." As for her own ambitions, Ms. Port may soon be joining the ranks of Lauren and Heidi with her own line, but details are TBD. For now, designing clothes is simply her "pleasure." Lo, meanwhile, sees herself hosting for 'nets like E! and Bravo, and Audrina has acting on the brain. To Patridge, her just-announced role in Into the Blue 2 is a "stepping-stone" that might lead, she hopes, to a career like Charlize Theron's.

Despite all the plans and drama to come, however, all of it - ok, most - was on hold during Monday's soirée. For one brief night, Hollywood's young reality royalty lived it up and celebrated the show's success, together. - Anna Dimond