for people across the country or world for that matter for young people to come on and share photos of themselves and video. Or should I focus on the Atlanta area. Would I get enough members with a more local direction?
I'd focus on local/regional! Similar to what I plan on doing for a racing site, distinguishing regional areas across the country and draw them all into the 'mother site'.
Local is a much better solution, because there are 10000s of these networks for international. I'm personally going to do a personal one for my country.