[RussP]

Has it occurred to you that your screen name has an annoying grammitical error? Sorry, but it just bothers me. You don't say, "a NYC guy. You say, "an NYC guy." If you spell out New York City, then you precede it with "a," but for the acronym you use "an," because "N" is pronounced "en."

[aNYCguy]

Has it occurred to you that your screen name has an annoying grammitical error?

Has it occurred to you that your spelling of annoying grammatical error has an annoying spelling error?

But seriously, I chose "a" because, as you expected, I think of it as "A New York City Guy" and don't consider the space-saving acronym something which would be pronounced.

And besides, it's my favorite indefinite article. So streamlined! So elegant!