I accidentally stumbled across Century 21 a couple of weeks ago when I was in NYC and have forgotten to pack any kind of long sleeved/buttoned shirt. I found passable shirts that I will most likely return to Argentina with for a paltry sum of US$19.97. (~AR$90) Anything comparable in Argentina would have been over AR$150 and lower quality. For better shirts, you would be looking at ~AR$200-AR$250. (Again, not great shirts, but passable.)
Also, I was constantly blown away by the architecture in NYC. Have lived in BsAs for 5 years now and having given tours for well over 3, I'm always looking to walk down new streets and almost always have a camera on hand to photograph cool new buildings. But New York was ridiculous! Everything is on such a bigger scale than Buenos Aires that I was blown away. (And it's so much more bike friendly too.)
Your wife can still use her Spanish in NYC, however maybe not EVERYWHERE like in Miami.