It may have been the middle of the Depression, but Park Avenue developers had lots of recently constructed apartments to push, as these ads in the July 4, 1936 edition of The New Yorker demonstrate.
This one below, for a Murray Hill building, features an “interesting” floor plan. The dropped living room feels like a 1930s design innovation:
This ad on the left targets “the family with a debutante daughter or several children” and includes the kind of lifestyle illustration developers love using in ads today. On the right, no fancy copy; just some “smart”and roomy uptown apartments. I wonder how “reasonable” $3000 a year for six rooms really was.