Exclusive Feature: With each generation there's a new set of expectations; no where is this truer than in the travel industry.

Harris Interactive polled 8,535 employed adults online in 24 countries between Aug. 20 and Sept. 12, 2013, to get their impressions and preferences on travel.

The focus was on Millennial travelers - the next generation of luxury travelers, according to some hotels and airlines - because they're projected to become the most influential and profitable traveler set. They travel a lot more (and spend a lot more) for business and pleasure than travelers ages 31 to 45, and that's only going to grow as they mature.

According to the study, Millennials aren't just spending more when they travel - they're complaining more, too. Millennials (18-30 years old) seem to be slightly more high-maintenance than generations before them, if you believe the study, which was commissioned by Expedia.com and Egencia, its business travel sister company.

Millennials don't skimp when it comes to hotels and amenities, either. 37% said they would spend more of their company's money on room service, compared with 21% of those between the ages of 46 and 65. As for food, they have pretty fine palettes. Millennials (42%) will spend company money to pay for high-end meals, compared to 26% of their older peers.

However, the free-flowing budgets of Millennials could come at a cost to hotels. They spend more, but they also complain more, the study found.

Thanks to the advent of social media, Millennial travelers are more likely to voice their opinions online -- 26% of those 34 and under surveyed said they had posted a negative review within the last year (compared with 14% of their older peers) and eight in 10 Millennials find travel reviews to be "very important" or "somewhat important" when they book their travel.

For all their quirks, however, Millennials have one thing going for them that older generations seem to have lost: the ability to successfully merge business and leisure travel.

More than half — 62% — extended a business trip into a personal vacation. Note to hotels: this is where those weekend upgrades and loyalty offers really pay off!

This is strictly an exclusive feature, reprints of this article in any shape or form without prior written approval from 4Hoteliers.com is not permitted.

Melanie Nayer is a hotel reviewer and expert on luxury travel around the world. She has covered all aspects of hotels including corporate restructures, re-branding initiatives, historical aspects and the best of the best in luxury hotels around the world.

Melanie writes a weekly exclusive column for 4Hoteliers.com