We've come a long way from casual Fridays. Nowadays, CEOs are rolling out big perks to keep employees happy: Think three-day weekends every week, tropical "workations," and bonus money that you can only use if you take a vacation.

And it's not just cushy start-ups boasting plush amenities, but all sorts of companies — including PR firms, ad agencies, and even cosmetics and e-commerce businesses.

These perks may sound extravagant, but they can pay off in the long run. The more that CEOs invest in their employees, the more likely they are to hold onto them for the long haul, which can lead to lower turnover and monies saved on recruiting and training costs. Ideally, these cushy benefits will deter people from wasting company time and prevent burnout.

Billion-Dollar Burnout

“About three-quarters of employees have engaged in some type of counterproductive work behaviors, and many others experience stress, exhaustion and even burnout,” said Manuela Priesemuth, assistant professor management and operations at Villanova School of Business. "The costs for companies in lost productivity each year are in the billions."

Research in the realm of organizational psychology and behavior has shown repeatedly that employees who feel valued and taken care of by the firm are more loyal and more productive in the end, Priesemuth told NBC News. "From a work psychology perspective and likely from a profit perspective, it might indeed make sense for companies to invest in some of these policies and attempt to create a better work life for employees,” she said.

All Work and No Play? Prepare to Fail

Generous policies certainly made sense for Alex Slater, CEO of the PR firm Clyde Group. Before he implemented perks, his employees were miserable — and they didn’t last long.

“After our first year in business, we lost half our staff, [and] a dramatic staff survey showed that most staff reported working over 60 hours a week, and that they were unhappy about working at the firm,” said Slater. ”They rated the culture badly.”

Related: Flexible Hours Rated Most Important Perk at Work

Slater held a company meeting to address all the concerns, and in came the perks: A maximum of 40 hours a week (not an obvious perk, but a perk nonetheless, especially for salaried workers); an unlimited budget for personal development (conferences, training courses, tutorials, leadership training), plus unlimited time off to take part in these development activities; a $150 monthly stipend to pay for the gym or other activities, and a mandatory five-week sabbatical program and $5,000 stipend with the sole work requirement being “make us jealous.”

With these perks in place, Slater said staff turnover has reduced to zero, growth has surged, the caliber of recruits has heightened, and employees rate the culture as “excellent” when surveyed. Plus, the firm was shortlisted for PRWeek’s 2017 Boutique Agency of the Year.

“I attribute [these gains] entirely to better work/life,” Slater told NBC News.

Take It on the Road

Jason Myers, a touring musician and senior account executive at the Content Factory, was jumping from job to job before he joined the Pittsburgh firm in 2010. What did the trick? The work-life culture of the company that enables employees to work remotely — even from exotic destinations.

“As with all employees [at the Content Factory], I was able and encouraged to do my job remotely, so long as I was getting results for the clients,” said Myers. “[CEO] Kari DePhillips extends the same benefit to all employees and we take full advantage. One co-worker just returned from a trip to Paris and Morocco. Kari herself is currently ‘workationing’ from a new country each month this year along with a colleague, and has invited the staff to workation with her in places like Mexico and Puerto Rico when our Northeastern climes get too chilly and oppressive.”

Bonanza, an e-commerce platform, doesn’t offer full-time remote, but during the month of February, the company physically moves to a tropical location. All employees (plus their families) are invited to enjoy “Freedom February,” and are provided a bonus that can be used for the workation. They are also allotted extra personal days in February to enjoy some time in the sun.

Wow, that sounds… expensive. How can a company that isn’t in the ranks of, say, Google or Facebook afford this?

“I'd be lying if I said that evaluating financial sustainability came first when we created the benefit,” said CEO Bill Harding. “It's hard to make a formula that proves Freedom February is a financial victory, not least because we have experienced small-but-measurable declines in productivity during February.”

That said, from a big picture perspective, Freedom February is one of Bonanza’s most valuable investments.

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“This benefit is probably our best recruiting tool,” said Harding. “Friends of friends see the pictures on Instagram and hear the stories afterwards. There's also a degree of good will created by a unique benefit like this.”

Bonanza also allows its employees to work remotely every Wednesday, an option that workers of all ages are seeking.

“Millennials are certainly a driving factor in the growth of remote work, but interestingly, their desire for flexible work options is only slightly higher than that of Gen X or baby boomers,” said Sara Sutton Fell, CEO and Founder of FlexJobs and Remote.co. “In a 2016 survey, we found that, when evaluating job prospects, 82 percent of millennials cite work flexibility as a factor compared with 81 percent of Generation X and 79 percent of baby boomers.”

Tourists enjoying white-water rafting in Turkey. Sovfoto / UIG via Getty Images

Not Using That Unlimited Vacation? Let Us Pay For the Vacay

Unlimited vacation policies are an increasingly popular “perk,” but they can backfire. Employees may not feel they can afford to take the time off, or that they’re asking for too much and so end up taking less time off than they would at a company that has a set amount of vacation days per year.

Mark Douglas, CEO of online marketer SteelHouse, decided the best way to give his employees unlimited vacation — and ensure that they would use it — was to give them money for their vacations.

“Buy your plane ticket on Monday and we’ll reimburse you in full by Tuesday,” said Douglas. “Can’t front the money yourself? Here, use the company credit card. I want you to actually go somewhere and enjoy yourself.”

SteelHouse offers employees a $2,000 annual vacation stipend — and if you don’t use it, it goes to waste.

Matt Rissell, CEO and co-founder of time-tracking company TSheets, also pays his employees to take vacation — $1500 per year, per employee. The caveat? You have to completely disconnect while you’re on vacation: No calls, no emails, no Slack — or you lose the bonus.

“27 employees have taken advantage of this benefit so far in 2017 — and I can assure you this requirement is strictly enforced,” said Rissell.

Ervin & Smith also gives its employees vacation money in the form of a $1,300 Visa gift card. The money must be used toward travel, which Ervin & Smith president and CEO Heidi Mausbach feels is essential to creativity and helps employees “not only to reset, but to open our eyes to a new view — literally and figuratively — and return more positive and productive.”

Three-Day Weekends and 30-Hour Work Weeks

Who among us has not come back from a three-day weekend feeling remarkably refreshed? Some CEOs see the positive difference a short week can make, and have made that happen for their employees.

SteelHouse has a three-day weekend once a month. And Cockroach Labs’ name may make you want to run away, but their four-day week is pretty inviting.

Rhonda Allison Cosmeceuticals lets her employees take every Monday off.

"In our industry, most aesthetic professionals and spa owners take Mondays off to recoup from busy weekends, so it was a natural day for us to take off as well,” said Rhonda Allison, founder and CEO.

Other companies quantify a full work week as fewer than eight hours a day.

“We work ‘Swiss hours’ from 11 am to 4 pm, which is enough time to get all of your work done without any wasted time,” said Clarke Bowling, digital marketing manager at eXO Skin Simple. “It also gives you enough time to get in a workout before work (we regularly brag about how many miles we got in before our start time), plan a week-long juice cleanse, or work on a passion project.”

Related: Want to Trade Overtime for Days Off? Congress Mulls an Overtime Pay Bill

Andrew O’Brien, CEO and founder of The Publicity Guy pays his team a full-time salary for a 30-hour workweek.

“[Employees] also choose their own schedule as far as what hours they work,” said O’Brien. “They are more productive and willing to work hard than if they worked eight-hour days, five days a week.”

Some companies keep the eight-hour days, technically, but assign one of those hours (in addition to a lunch break) to be used for non-work.

"I instituted ‘self care hour’ and so far it's worked well. Everyone in the company has the same hour off (we work across several time zones) and my staff has the freedom to do whatever they want during that hour — except work," said Jo Jensen, CEO and founder of Causeumentary.

Jensen was moved to implement the self-care hour when she noted that her female employees admitted feeling guilty when they weren't working. "They can watch TV, grab food, hang out with friends, exercise, get a manicure, walk their dog, etc. I generally go for a bike ride, walk my dog, or catch up on one of my favorite TV shows on Hulu. I find when I get back to work, I'm much more relaxed — and my staff is too."

A passenger travels on a scooter with his luggage at Heathrow airport in London. REUTERS/Luke MacGregor Reuters

Hey, the CEO Likes These Perks, Too

CEOs don't just offer perks to keep their employees happy and productive; they offer them to keep themselves happy and productive, too. CEOs — they're just like us!

Kristi Piehl, CEO of Media Minefield, decided to allow new moms and dads to bring their infants to the office in part because a family-friendly workplace aligned with her own priorities.

"I wanted to create a company culture I actually wanted to, and could, work in," Piehl told NBC News. "I was a TV reporter when both my boys were born so [bringing my kids to the office] wasn't an option, but in the kind of environment we have at Media Minefield, it would work. So we gave it a try and so far, so good."

And many CEOs have experienced their fair share of burnout. They don’t want to foster an environment that promotes overworking.

Related: Three Reasons You Feel So Burned Out at Work

"I have worked 24/7 since I founded my first PR firm, and a little over a year ago I ended up in the hospital," said Carol Bell, CEO of BrandLink Communications. "I am not saying my work caused my illness, but I do think the daily level of stress contributes to how your body responds to illness and the healing process. I appreciate my colleagues so much and I don't want anyone to learn the importance of balance the hard way that I did."

In addition to a Work From Home Friday program, Bell leads regular team-building activities that reinforce health and well-being — whether it's SoulCycle or a meditation class.

"These type of activities sometimes require a later start or an earlier ending to the day — but in our particular field, the days tend to be long and it's really important to take the time to recharge," said Bell. "I am living proof of that."