A tipster points out an interesting quirk in the floorplan at unit #9DE at 15 Union Square West: after the combination of the two units, there's "essentially a studio apartment inside a 3-bedroom home." Some possibilities: an in-law or nanny suite, or "a sweet AirBnB rental," as our tipster notes, but shhhh, we didn't suggest that. The combo, a rarity within the building, is asking $9.17 million for four bedrooms, four and a half bathrooms, and a total of 3,100 square feet. The common charges are a hefty $4,608/month, plus another $3,389/month in taxes. We'll admit we like the staging here better than in some other 15 Union Square West apartments we've seen.