I would definitely not go to Japan, I'd rather have Aussie DLC or British DLC if it came to it myself. Since I live in Vancouver obviously DLC Vancouver would be fine with me and possibly even would help host it.
Hmm, just a quick look at flights from San Francisco to Tokyo/Sydney/London:
England: $1300 (best deal) $1400 (average deal), 12 hours
Japan: $900 (best deal) $1900 (average deal), 14 hours
Australia: $1400 (best deal) $1500 (average deal), 17 hours
From Vancouver, England will be shorter and cheaper. Japan might be shorter/cheaper from Vancouver but I'm not sure. Australia is probably more expensive.
If we're doing a crazy overseas location, I'd vote for one in the Northern Hemisphere. Cutlural experience aside, the airfare is just going to be cheaper/shorter. Although...hold that thought, let me look up Rio...
Brazil: $900 (best deal) $1100 (average deal), 15 hours
Hmmmmm...other than the complete lack of direct flights, that's actually not bad from North America, and it probably saves Grefter...*does some research*...okay no, flight routes between Australia and Brazil suck, and are longer and more expensive than Australia to San Francisco.