At 48, George Lopez has starred in his own hit sitcom, amassed a loyal following over 27 years as a stand-up comic, and, most recently, joined the suddenly contentious ranks of nighttime talk-show hosts with Lopez Tonight on TBS. Why not add a surefire blockbuster to his résumé?

That’s what Lopez was thinking when he joined the A-list cast of Valentine’s Day, in which he co-stars as a florist’s assistant with Ashton Kutcher, Julia Roberts, Jamie Foxx, Jennifer Garner and Jessica Alba, among many others. That, and he wanted to work with director Garry Marshall.

“Think about it – Happy Days, Laverne and Shirley – how many years have you seen Garry Marshall’s name in the credits?” Lopez asks. “I met Garry at Dodger Stadium during the Hollywood Stars game. He loves baseball. And I loved Nothing in Common, the movie he made [in 1986] with Jackie Gleason and Tom Hanks, near the end of Gleason’s life.

“When I read the Valentine’s Day script, not a lot of celebrities were attached yet. But I liked the story, and I like Garry.”

Lopez admits he’s not usually first in line to see romantic comedies, though his wife is a fan. In the case of Valentine’s Day, he says, it would be hard to resist the allure of such a glamorous cast. “It’s also a perfect date movie if you want to cash in,” he adds with a laugh.

In the movie, almost all the characters find their faith in Valentine’s Day shaken by some regrettable twist of romantic fate. Is Lopez a believer?

“I’m married, so I have to celebrate the holiday, but I try to take care of my wife at Christmas,” he says. “Go all in with the presents on that day, and maybe two months later you’re off the hook.

“Personally, my favorite holiday is the Fourth of July. There’s a lot of drinking outside and a lot of burning meat. That’s all you need. That’s a real party.”

For the newest face of nighttime talk, the movie has another advantage: supplying him with an enviable lineup of guests. This week, co-stars Kutcher, Topher Grace, Hector Elizondo and Garner appeared separately to promote the film, with Garner recreating for Lopez's audience a memorable Valentine's Day sequence in which she angrily pulverizes a piñata.

With Lopez Tonight gradually gaining steam and his eponymously titled sitcom still pulling strong numbers in syndication, the comedian says this is the most rewarding moment of his career. He enjoys the thrill of working before a live audience, though he admits it doesn't feel like work to sip cognac with Chris "Ludacris" Bridges, as he did during a recent interview.

But don't expect him to get mired in the late-night verbal skirmishing over NBC's decision to return The Tonight Show to Jay Leno – though he doesn't shy away from the subject, and he doesn't mince words.

"I don't think it was fair for Leno to go to 10 o'clock and disrupt what Conan O'Brien was trying to do. It's important to get first dibs for that audience, and Leno was essentially eating off Conan's plate. Leno isn't getting a lot of love right now, and I understand why.

"I've been hosting a talk show for a little more than two months, and that's no time at all. You need time to build an audience. Leno did that show for 17, 18 years. I don't know how long I want to go with my show, but I'm thankful for the opportunity to try it, and to be in a big comedy like Valentine's Day at this stage in my life. What could be more exciting?"

Bonus Sound Bites

"I think Valentine's Day is actually a very unromantic day because you can't really force romance. It just has to happen naturally.               
There is so much pressure to make that day special and have a good time, it's virtually impossible to have one." – Patrick Dempsey

“Somewhere around the time we had our second kid, I thought, ‘This is really turning into something.’” – Jennifer Garner, on when she realized her best friend, Ben Affleck, was the love of her life

“There wasn’t a Valentine’s Day that went by on That ’70s Show when I didn’t get a card or some roses.” – Topher Grace, on whether Ashton Kutcher is a true romantic

“We’re just going to be making out – for the full 24 hours.” – Julia Roberts, on her holiday plans

“Coming from a long line of Valentine’s days, a long line of cities where I’ve experienced Valentine’s days, and also a long line of partners, I would say the key to a good relationship is a husband who looks the other way.” – Shirley MacLaine

“I would recommend a piñata.” – Garner, on the best way to work out post-breakup frustrations

“I think it’s the same in any city. L.A. isn’t distinctive in its uniqueness when it comes to making relationships work – two people who work at it. That’s true in any town you go to.” – Roberts, on how to make a relationship work

“Love in L.A. is different. When I first got here, when I needed a name tag, trying to date was pretty interesting. I met this girl on a Monday, it was incredible – we partied, kicked it, went back to my crib and made love. After that, we cuddled and talked. That was Monday. When I woke up, I smelled something – she was cooking me breakfast. It was great.

“Back then, there were no cell phones, just landlines. So I didn’t call her Tuesday, and I didn’t call Wednesday. On Thursday I saw her at the club with another guy, and she spoke to me – ‘Hey Jamie, how are you?’ And she introduced me to her man, and she’s like, ‘He has a Range Rover just like yours, only it’s this year’s!’ So it’s interesting.” – Jamie Foxx, on his first romance in the City of Angels