While it’s unlikely to ever become a standard hotel feature, flexible check-in and check-out is an obvious traveler-pleaser. Really, who wants to be locked into the hotels’ arbitrary definition of when a hotel stay can begin and end?

Hotels are well aware of the demand for such flexibility, and indeed have made it a perk of elite status in some loyalty programs. But the practical challenge, of staffing for round-the-clock housekeeping, has kept the practice from proliferating. It’s too complicated and too expensive to offer throughout the extensive networks of major hotel chains.

Taking advantage of it small size, Standard Hotels, with just five properties in Los Angeles, Miami, and New York, this week introduced Standard Time rates, “a spanking new service that lets you choose your check-in and check-out times.”

According to Standard’s website:

When selecting the room type, you’ll be given the option to choose Standard Time from the drop-down menu if it’s available… For a small fee, you get all the benefits of coming and going at your leisure. Prior to your stay, we’ll get in touch via email to get your estimated check-in and check-out times. How you use your Standard Time is up to you.

That “small fee” may not be so small. In random test bookings, the extra charge for a Standard Time stay ran the gamut. For example, a mid-week night at the Hollywood Standard in early August is priced at $259, rising to $276, a 6.6 percent surcharge, for the Standard Time rate. For the same period, a standard room goes for $333 at the Standard High Line in New York, whereas the flex rate is $388, a 16.5 percent premium.

A surcharge may be the key to making flexible hotel stays widely available. But it should be a predictable extra cost and a reasonable one—a few percent of the base rate, say, or a flat $25.

Reader Reality Check

What’s a reasonable surcharge for flexible check-in and check-out?

After 20 years working in the travel industry, and almost that long writing about it, Tim Winship knows a thing or two about travel. Follow him on Twitter @twinship.

This article first appeared on SmarterTravel.com, where Tim is Editor-at-Large.