1 floor, duplex or triplex?

All on one floor is best. Don't know your age but when the knees or hips bother you, you won't like the stairs. Even if there is an elevator that's sharred you may not like using it in your pajamas.

Also, any outdoor space should be off a common area and not your bedroom. Not fun when guests have to go through your bedroom to get to the terrace.

Stairs keep you young.

I've always liked the separation between the sleeping and living areas, particularly with children with naptimes and early bedtimes.

i think people prefer multi level homes because they feel bigger and, like matt said, there's a separation of areas that serve different purposes. also, it makes people feel like they live in a real house and not a stacked box.

But unless you're buying a lot of square feet, those stairs take up room. To me, a one floor unit feels more spacious that two or three floor units of the same square footage. Unless there are fabulous windows.

To lef's point. A lot of wasted space. If everything else is equal (building quality, location, views, light, height ...), a duplex or triplex will have fewer usable rooms for the same square-footage as a one-floor apt. That translates into less $/sqft.

If you want to research this price differential, look into buildings that have duplexes-as-built and simplexes and compare price/sq. ft. You're not generally paying more for the "wasted space", so it's really a personal preference.

If you're splitting hairs to such an extent that you're computing price per square foot for how much space the stairs take up, you are most likely overextending yourself and looking at apartments you really can't afford in the first place.

The original question was whether there was a price differential. My answer is that price/rooms given everything else equal is the same. Price/sqft is different because of wasted space. Why are you jumping to affordability?

Because you cannot always boil every apartment down to price per square foot.

They were usually built because enough people liked a staircase and would pay a bit more for it than a simplex of the same size. Take the S line at 25CPW, where a stack of LR/K is next to a stack of BR/B, with an enclosed curving staircase in between. Relatively efficient, because the staircases are stacked with no wasted volume above them, but still use space that could've gone to closets or something. It would've been cheaper to build simplexes in the same horizontal space, but the builder figured there was a market.

The same kind of offset duplex is at 610WEA, 3E69th, 4E70th, etc.: a whole range of prewar buildings.

Then there're a lot of standard one- or two-bedroom duplexes where the leftover available width would allow only a studio at a time when studios didn't sell, so the builder would make a duplex with a pretty curved staircase instead of two studios. The staircase is invariably in the dark hallway end of the apartment, so all you lose is some storage space.

A third kind would be the intentional duplex, where space isn't much of a consideration and the staircase is very much an expensive-to-build feature. E.g., 740Park and 812Park, where almost everything's a duplex and the simplexes fill in the leftover space.