With the whole "war" between the NY capos after Big Carmine's death, one could compare them to the Colombo's.

But like Phat said, the whole "whack Jersey" plotline, where else could Chase have lifted it from? Personally, I dont think its important which family exactly they're supposedly based as much the idea of the NY element they represent. The "establishment".

Soprano's was great, but as far as dead on realitic with mob politics...I dont really think so.
I think Chase did a great job but; and if you think about it, there's pretty much a handful of possible real life contenders for just about every gangster on the show, especially when you use the average guidelines. I think Chase was in a position to pick and choose the things he wanted his mobsters to experience. The Families in The Soprano's are composites, with a healthy dose of creative licence..