Chicago is home to a great community of minis players. You might recognize a few of the best competitive players from this local in the names of Fingersandteeth, TimmerB, MtMagus, and myself. Then you add on about 6-8 locals that play weekly or monthly around the city, and several others not too far such as Princeton and Milwaukee, and heck, we travel to Gencon in Indy, and occasionally to Kalamazoo to play with the likes of Engineer, Uliq-Quel Droma, JDJersey, and others.
So if you come to Chicago, you are in for one of the strongest and most active communities around the world.
I can tell you nothing about New York