Vietnam is where China was about 20 years ago. It's got a population of 90 million and about 70 percent of the population is under 35 years old, great demographics. They are basically like Chile or California in terms of geography (one long coast) and resource rich.
It has a lot going for it. I know you seem set on China but I just wanted to throw that out there since people seem to be talking about alternatives (myself included, see China vs. Brazil Showdown thread).
No matter what overheating, inflation, social unrest, pollution, or severely fucked up demographics does to China, it will match and then surpass the US inevitably. As such, I personally view China as not a short term play but as a global player that I need to become intimately familiar with. It helps that I already have substantial experience there at my age.
My lack of mandarin fluency is also making it difficult for me to get jobs I want at an attractive salary in Shanghai and Beijing. I have been increasingly looking at second tier cities like Dalian and Chengdu. There is a range of second tier cities, I'd say 10-20 depending on your definition and who you are talking to. They are considered integral to the next wave of massive development in China.
http://www.china.org.cn/english/China/230323.htm
In a lot of these cities the foreigner advantage that was so prevalent ten years ago still exists for expat willing to step outside their comfort zone. I've experienced both Beijing and Shanghai and would value work experience in a second tier city just as valuable, but in different ways.
One thing that is commonly happening to a lot of my expat friends in Beijing and Shanghai is that they are getting ridiculous promotions in very short periods of time. I'm talking about twenty somethings who lead departments on projects they would need an MBA and 8+ years of work experience to get in the US.
Ex. American student who went to college with me, did a post-bac language program in Beijing, then randomly ended up in a nuclear consultancy. In 2.5 years of working went from entry level to senior project manager and regularly sources parts for next generation nuclear power plants with Korean and Dubai-based nuclear developers.
Only in the emerging markets - there is no time like right now to get out there.