Companies weigh the pros and cons of business travel vacations.

Hilton CEO Christopher Nasetata noted during a recent earnings call that more guests are taking their vacations on business trips. Marriott CEO Tony Capuno said Thursday and Sunday nights are around the beginning and end of many business trips, proof that guests are extending their stays.

The availability of remote and hybrid work makes dual-purpose trips more attractive, says Debbie Inacci, head of communications and research at the Global Business Travel Association. A July survey by her company found that 90% of travel managers said their employees wanted trips that combined work and leisure.

That demand comes as demand for business travel generally declines. A July survey of nearly 400 international business travelers conducted by hospitality data and analytics company STR found that 55% are less likely to travel overnight for business than before the pandemic.

Mixing work and play is challenging, especially when the company is covering a lot of expenses.

But most companies still don’t have formal rules for adding vacation travel to work travel. An April survey from the Global Business Travel Association found that 49% of travel managers said their company’s travel policy does not cover mixed travel. In most cases, employees may leave with their supervisor’s permission.

Corporate-travel experts say companies are uncertain about the risks they and employees face with more dual-purpose trips.

“If you’re on a business trip that you’ve extended by a few days and you’re injured, there’s a very interesting question about liability,” says Charlie Sultan, president of Concorde Travel, a corporate-travel management company. “Are you on a business trip or is this part of your fun time?”

Paul Tumpowski, CEO of Skylark Travel, a New York-based travel agency, says concerns over accounting and billing are preventing widespread formal adoption of corporate travel policies that allow mixed travel. Analyzing legitimate business expenses and personal expenses can require a lot of staff and oversight, which can be costly.

Not providing regular support for these trips means that employees are left to their own devices as they sort out the logistics. And that can be complicated.

Pat Scaramuzza, a scientist who lives outside of Minneapolis, traveled to Italy in June to attend a conference with his wife and two grown children. The manager let him control his time off.

He and his wife bought plane tickets directly from the airline, later learning that Mr. Scaramuzza had to buy them through his employer’s travel agent. He had to return and repurchase the ticket, making sure it was for the correct flights.

“There was one flight where we didn’t sit together,” Mr. Scaramuzza says. “It was just like that.”

When he was in Italy, he had to make sure he split the hotel bill, he put some on his corporate card and the rest on his personal card.

Despite its complexity, integrated corporate travel has become a selling point for some companies looking to hire new employees or retain existing employees, said Greeley Koch, managing director of 490 Consulting, a Chicago-based consulting firm.

“Companies in a tight job market want to retain talent,” he says.

He said this move to benefit from integrated travel has led many employers to begin formalizing travel rules.

When Rick Sharga was asked to speak at an August conference in Las Vegas, he brought his wife for an extended date night the week before to celebrate their anniversary. He was scheduled to give a speech on Monday, so the couple spent the weekend in Vegas, visiting some of their favorite restaurants and shooting a couple’s massage at their hotel. The congregation paid for Mr. Sharga’s flight and part of his hotel bill.

“When your other regular expenses are covered, it puts a little bit of restraint on your spending,” said Mr. Sharga, executive vice president of market intelligence at Atom Data Solutions, a California-based data company.

Work hard and have fun

Planning a workplace? Here’s travel experts’ advice on how to make your trip a success.

Clear the policies first. Review your company’s travel policy, and ask your supervisor questions. Pay attention to what your company’s responsibilities are if problems like a canceled flight or a hold-up with a rental car occur, and how your company handles these situations if your trip is extended for fun.

Track expenses. Before the trip, decide what the company will and will not pay. If your company prepares daily for business trips, keep a close eye on your expenses. Don’t put personal expenses on the corporate card.

Predict your productivity. Not all work trips should turn into vacations. Mr. Sharga, who averages about two business trips a month, often avoids bringing his family if he finds out he is in a meeting.

“You worry more because you’re not spending time with your family when they’re there,” he said.

Write to Jacob Passy at jacob.passy@wsj.com