For really large apartments, size can be its own problem. This Chelsea loft’s huge footprint (5,000 square feet) left a big, dark center far from the perimeter windows. We fixed this by pushing the habitable rooms to the windows and packing the middle with storage. Then we ran a ring of circulation between the two zones.

Instead of side walls, the family room has giant etched glass panels that pocket away to clear a path for the kids’ zip line. For the adults, there’s a sound-proof music room, a climate-controlled wine room, and plenty of clean, modern detailing.