I toured Grand Concourse for about 30 blocks on Streetview, and the deco didn't really jump out at me. It's a very impressive street due to the continuous, unbroken street wall, but it doesn't scream art deco like I was expecting it to based on some of the replies in this thread.
This building is pretty clearly art deco inspired:
https://www.google.com/maps/@40.8366...7i16384!8i8192
But if you turn the camera around, basically everything else you can see is not done in the deco style. That said, I'm sure NYC has the most art deco buildings, because they have the most buildings period- especially buildings from the 1920s-40s.
I think Los Angeles has some really great art deco structures. The city was really in its first big boom period in the height of art deco's popularity as a style. From the iconic blue Eastern Columbia building (
https://www.google.com/maps/@34.0425...7i16384!8i8192) to this stunner in the Jewelry District )
https://www.google.com/maps/@34.0466...7i13312!8i6656) to the Bullocks Wilshire in Westlake/K-Town (
https://www.google.com/maps/@34.0617...7i16384!8i8192), LA has some really stunning examples of the style.