I do not know exactly, but I guess the most appropriate countries in as Japan, Spain, china and Usa, Maybe I can add hong kong and singapur to this list. I thought to meet the needs of the tourists in the regions where tourism is concentrated.
You cant really tell which country trade most in bitcoin, but if I should guess, I will say its likely to be Japan and China. According to a source I read online, Japan was the reason for the price boost around that August 1st, so they are the number one.