I'm not sure how I picked it up, being from Philly and Maine, though I consider Maine to be kin to the South. Of all the terms for inclusively addressing a small group of people, in a way that each person knows that you are not singling out any individual; I think y'all is an excellent term. The problem of course, in its association with an often stereotyped part of culture, is that it can be interpreted variously as a joke, a sign of poor vocabulary or education, or even an insult to those addressed (or to The South) (or even to African Americans). In situations where one is offering service to a group of people, whether in your home or at work, many alternate expressions infer subordination to those we address. And terms like "you people", "you all", or "everyone"; have a formality and stiffness that can sound condescending or superior. So I think "y'all" is a fine upstanding term! Still, my thinking seldom saves me from looking like a fool. And I end up a closeted y'all sayer.