When traveling on business, millennials are more likely than older employees to add vacation days onto the trip and to spend more of their boss' money than their own on items such as room service and expensive meals.
Workers under 45 also feel more entitled than older employees to the loyalty program and reward points earned while traveling for business.
Those are among the findings of a study released Monday by Expedia.com and its business travel company, Egencia, that asked 8,535 employed adults in 24 countries about their likes, dislikes, preferences and pet peeves when traveling.
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The study was conducted online by Harris Interactive between mid-August and mid-September across Europe, North America, South America and Asia-Pacific.
It sheds light on the experiences of business travelers of all ages and found, for example, that 39 percent report working more hours when they travel than when they are at the office, and that 68 percent receive some sort of compensation (either money or comp days) for trips that include nights and weekends.
But Expedia spokeswoman Sarah Gavin said the study was specifically designed to look at younger travelers who are poised "to gain decision-making power within corporations and, as their careers rise, buying power in leisure travel."
Understanding what these tech-savvy and -trusting millennials want "will inform how we think about what will matter in the years to come," she said.
It's no surprise that 75 percent of travelers report using smartphones and tablets on the road for both business and personal reasons, or that those 18 to 30 are more likely to do so.
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But, Gavin said, Expedia was surprised by how much more likely millennials are to spend their employers' money on hotel upgrades, room service, and high-end food and wine.
According to the study, 42 percent of those 18 to 30 spend more company money than their own on pricey meals (versus 26 percent of those 46 to 65); 37 percent of the former age group spend more company money than their own on room service, versus 21 percent of the latter group.
Expedia also noted how critical loyalty points are to millennials.
"In particular, younger workers are more likely to belong to loyalty programs than their older counterparts, even though they've obviously been road warriors for a much shorter period," Gavin said.
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The results the Expedia/Egencia "Future of Travel" study generally mirror the findings of the "Traveling with Millenials" study released in March by The Boston Consulting Group.
The authors of that study point out that though millennials are not yet the core customers of airlines, hotels and travel companies, "they will be in five to 10 years, when they enter their peak earning, spending and traveling years" and that suppliers "that don't reach out to millennials now, seeking to understand and address their unique needs, may miss the boat entirely."
—By Harriet Baskas, Special to CNBC.com. She is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas.