Ashton Kutcher Went on a 'Crazy 10-Day Road Trip' with Mila Kunis and Kids to National Parks

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Ashton Kutcher isn't in a rush to get his kids back to school.

During the Los Angeles premiere of his new film Vengeance on Monday, Kutcher, 44, spoke to PEOPLE exclusively about the exciting summer he's had with wife Mila Kunis, 38, and their two kids, son Dimitri Portwood, 5, and daughter Wyatt Isabelle, 7.

"I have the best time with my kids," Kutcher shared. "If I never had to send them back that would be my preference."

The actor revealed that the family of five just got back from "a crazy 10-day road trip."

"We just went cruising in a van to the national parks around the country. Just hanging out with our kids 24/7 and it was phenomenal," he said. "But then you got to work too."

Kutcher also shared some appreciation for teachers when talking about the back-to-school season. "Their teachers are better teachers than I am," he acknowledged. "They gotta learn something."

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RELATED: Mila Kunis Reveals Her Biggest 'Parenting Fail' That Caught Husband Ashton Kutcher Off Guard

Last year, Kutcher revealed that he previously had a ticket to ride in one of Richard Branson's Virgin Galactic flights, which take civilians to the outer atmospheric layers of Earth. But Kunis told her husband that the voyage wasn't "a smart family decision," so Kutcher sold the ticket back.

"I was like, 'That's irresponsible, you cannot have… This is not what you do. You are a father,'" Kunis explained to PEOPLE. "I was all so hormonal and I was like, 'You can't, you're going to die. The thing's going to explode and you're going to die — and you're going to leave me with the babies.'"

Kunis asked him to return the ticket. "Being the sweet man that he was," Kunis said, Kutcher acceded.

"I know I hate it," she said of the decision in retrospect. "Also I'm such [Star Trek fan]. The fact that I didn't let him go into space was so selfish of me, but I was a new mom and I was like, 'You can't leave me and the babies.' And so that's where that decision was made out of."

She added, "I want everybody to know I probably would have let him go to space now, but now it's too late."