Given NYC's sky-high rent, I wonder what would happen to the real estate market if these apartments were occupied by full-time residents. It seems grossly inefficient to have an apartment sitting empty for that long, no matter how much money you have. I guess there aren't too many good options, since airbnb-style renting is probably a) illegal and b) frowned upon by the building. If I were these people, I'd just treat the apartment as an investment property and stay in a really nice hotel when I was in town.