3 weeks? Depends on what you like. Brazil & beachs = boring, the night life isnt good. Argentina? Great food, nightlife is A W E S O M E, not too many "historical" bullshit to visit during the day but who wants to visit such

China? My favorite for sure, but not during december unless you go to the south but you really dont wanna spend your time @ shenzhen or guangzhou, too boring and not that impressive unless you love electronics.
Shanghai? Cold but its as good as argentina, night life is great, i expect 2 weeks of night clubbing next september, along with my wife, it will just gonna cost us$ 8k
