Having grown up in "Ya'll" country I have to say that I prefer it to "You guys" (often used when all the company addressed are not guys) and "Youse Guys". But then, there's no accounting for taste. In the part of Virginia where I grew up "Ya'll" was used by natives in the plural sense but "outside" folks having a little fun with the expression would use it in the singular form. One confusing factor could be that the term could be directed to a sole individual but the user and the individual would understand that it was an invitation to the family.

I read recently that "Ya'll" was derived from a Lowland Scot expression sounding somewhat similar.   Does anyone know if that is possibly true.