Cameron and Ashton Bring “Vegas” to Westwood (Fashion Wire Daily)

Diaz, looking fabulous in a short, body-skimming coral-toned dress and high black pumps, also happily greeted the film’s other co-stars, Lake Bell, Dennis Farina, Treat Williams and Rob Corddry, with big hugs and kisses. Kutcher, who apparently left wife Demi Moore at home with the kids, looked sharp, too, in a dark plaid jacket and slacks.

But despite the fact that Ashton did not bring his wife along to the premiere of the romantic comedy about a couple that marries in Vegas the night they meet, then immediately regrets it, he made it clear to reporters at an earlier press day to promote the film that in his personal life, he has no such regrets.

"I never thought in my life I would get married," the 30-year-old admitted. "I watched my parents go through a divorce and I thought ‘This is just not what people are supposed to do.'"

But then his path crossed with Demi Moore, and all bets were off.

"I never really understood the whole idea of marriage until I met my wife. I just knew that was the person I was going to be with for the rest of my life. I knew that I had that desire. I took the time then to understand it a little bit more of what it was about and I love it," he said. "I might be the most happily, I don’t know if happiliest is a word, I just made up a new word. I am the happiliest married man on the planet."

Joining Kutcher at the premiere was another famous face whose recent wedding was the talk of the town. Eva Longoria Parker came sans hubby Tony Parker, who is headed to New Orleans for the second round of the NBA playoffs. She greeted super-tall Vince Vaughn and Oscar winner Diablo Cody on the carpet, then all trooped into the theater to see just how well Cameron and Ashton paired up in the film.

Kutcher is pretty confident that audiences will love the combination; in fact, he happily likened "What Happens in Vegas" to one of Hollywood’s all time classic screwball comedies.

"What I feel like this reminded me of the most is 'Bringing Up Baby,'" he commented proudly. "Vegas" opens on May 9, so that’s when the world can judge whether Diaz and Kutcher are their generation’s Hepburn and Grant.