Prince and Greene, in the old Post Office. Decent restrooms up the stairs by the theater, but no changing table anywhere.
Use a bench of a corner of the theater area instead; there're always people lounging around, mooching the wireless, so you won't stand out.
And no ramp for strollers (nor for wheelchairs,of course). Very annoying.
There's a little lift on the right just before the steps when you step in the store. Not a ramp, but it serves the same purpose.