This is something I miss about New York city (real new york city). Somehow there is so much cultural protection and preservation there without total assimilation, but still it is like one giant family generally. Segregated and not at the same time, you can be anyone there and get along with everyone.
That'w what came to my mind when you said culture of cultures. Everyone in NYC is pretty clearly defined as to where they came from, but still everyone is considered a little bit Jewish, a little bit Italian, a little bit Irish, a little Puerto Rican, and so on. They can live separately and on top of each other at the same time. You can joke with anyone about their culture even throwing out some stereo types and have the presence of mind to know that you don't really believe it anymore than them, but have a laugh because you are all really one big family. I have been many places and I see NYC as the best at this. That being said most all of the melting pot in NYC are there to become their version of america, and add to variety, not to be against america because its evil.