I've only come across Aoki as a Japanese surname - '青木', meaning 'blue/green tree' or something like that.
Anyway, I have a couple of ex-pat friends and student friends out in Japan or studying Japanese. I haven't heard of Aoki being used as a first name, and I'm not sure if it can be or if it actively is.
Either way, I find it more surname-y. I also think it's a name best left to members of that culture.