I'm a little late to this thread- haven't been around YT much lately- but I live in NY too and my MIckey and Mallory LOVE yorkie meetups so our gang is definitely in!!!
I live in queens but I am fine traveling pretty much anywhere- Manhattan, Jersey... whatever!
Carl Shurz dog run is a good idea! I used to take Mickey there. There is also the dog run in the East Village in Tompkins Square Park. They usually have a very big dog run but it is undergoing renovation so they have a smaller temporary run up- i think its about the same size as the run at Carl Shurz- this may be easier for Brooklyn people to get to.
Wherever we end up picking I Can't wait!!!