When most people think of extended-stay hotels (if they think of them at all), they might envision a cheaply furnished room in a desolate location - cold comfort for bleary business travelers and depressed divorcées.

But, this underserved niche has received an extreme makeover in recent years, powered in large part by Philadelphia-based Korman Communities and its luxurious AKA chain.

Now, a former Korman executive has developed a new take on the concept: Roost Apartment Hotel, a boutique-hotel-meets-Airbnb vision.

It's all about the design, with un-hotel-like vintage accents, preserved architectural details, handmade antique rugs, oiled-wood floors and actual living plants. It's overseen from floor plan to furnishings by award-winning architect Morris Adjmi.

"We want the design to feel like this could be your apartment," chief executive Randall Cook said. "By bringing in things that are acquired over time, it has a layered [sensibility] that makes you feel like you're at home. If you're here for two months, you don't want to live in a generic hotel room. It has to feel curated."

The first Roost opened with 27 studios and one- and two-bedroom units at 15th and Chestnut Streets last summer; a second location at 1831 Chestnut St. is expected to be up and running with 27 more units, plus a restaurant, by September. Together, they constitute a $25 million investment - and, Cook expects, the basis for a nationwide expansion.

"I think we can do 20 of these in cities around the country over the next five to 10 years," he said.

The first location is housed on the fifth and sixth floors of the Charles S.W. Packard Building, which dates from the 1920s and also houses legal offices, three different condo associations, and a Del Frisco's Steakhouse.

Roost struck a deal with the Packard Grande Condo Association to renovate the lobby in exchange for the right to share it. Upgrades included new finishes and statement accents: a chandelier made by Brooklyn's Roll & Hill, and metalwork by Philadelphian Samuel Yellin that was found in the building's basement.

Upstairs, the space had been chopped up into city offices. But, hidden by drop-ceiling tiles, vaulted ceilings with ornate plasterwork remained intact.

Adjmi, whose projects include the Wythe Hotel in Brooklyn and a proposed boutique hotel in Fishtown, saw raw potential - and a unique opportunity for total creative control.

"I think that it's every designer's dream to be able to completely craft an environment, including the furnishings and the artwork," he said. "We can use design as a tool to create an environment that's nurturing."

Adjmi preserved what details he could from the historic building, and added such statement accents as herringbone-patterned wood flooring and built-in bookcases.

He designed the large furniture pieces himself, with sleek lines and low-slung proportions of midcentury modern styles - without making knockoffs.

"It was supposed to be slightly ambiguous," he said. "It was meant for everything to work together, to be eclectic."

So, a lacquer-finished, ultramodern kitchen, with appliances concealed behind slick paneling, coexists with a rustic kitchen island. In the bathroom, there is another time warp, where current touches such as frameless glass showers with rain showerheads are juxtaposed with classic penny tiles on the floor.

Adjmi and Cook decided on handmade Turkmen rugs for each room (it took local dealer David Dallas 10 months to locate ones that met the parameters), along with terrariums and container gardens designed by Terrain, and carefully sourced knickknacks on the shelves.

"It doesn't feel like this brand new furnished apartment or hotel room," Adjmi said. "We tried to make a place that felt better the longer you stayed, as opposed to a hotel that has a lot of flash and dazzle when you walk in, but then after the second day, you're tired of it. We wanted these spaces to reveal themselves over time."

To that end, Cook (who also went through "brand therapy" with consultant Alina Wheeler) obsessed for months over details: blackout shades, sound-insulated windows, metalwork by Amuneal, and a La Colombe-designed "coffee program" for each room that includes whole beans, a burr grinder and a Chemex, just to start.

He admits, for example, to having devoted significant consideration to the hangers, which were imported from Germany.

"It's, like, triple the cost of the normal hanger," he said, brandishing one from a bedroom closet. "But, when we looked at it, we were, like, 'You know what? This is a really nice hanger. It feels sturdy.' "

Christine Fitzpatrick, of Source Design in Chestnut Hill, was tasked with curating objects to fill bookshelves and side tables - vintage ashtrays, a dinner bell from a classic New York hotel, endless cloches and statuettes. She said it took about eight months to collect items that fit the restrained palette and eclectic aesthetic.

"I didn't want the eye to register busyness, just sort of richness," she said. "I wanted people to come over to the bookshelf and pick something up and say, 'This is really interesting. I wonder where they got that.' "

At the second Roost location, also designed by Adjmi, a similar process is underway.

"About 30 percent of the interior design will change. The rest will be the same," Cook said. "We wanted continuity but not a carbon copy."

After the first unit is complete, they will begin revising it. Then, they will adapt that design concept to the 26 other units.

It seems to be working. Roost has been fully booked so far, Cook said.

Part of that may be the market. According to a report by the consulting firm Highland Group, demand for extended-stay is on the rise, and number of units under construction nationwide, up 58 percent from a year ago, is still not keeping pace.

"Both the boutique hotel segment and extended-stay hotel segment are growing faster than the overall hotel industry. So to combine it makes sense in many ways," Highland's Mark Skinner said.

Roost's units go for $125 to $255 a night, with a one-week minimum, and the average guest has stayed for two months. (That's longer than the industry average of two weeks.)

Cook sees himself catering to people in often-stressful transitions, such as moving, undergoing medical treatments, or serving in temporary work assignments.

"If we can have design elevate someone's mood or ease someone's period of transition, that's a worthwhile goal."