thanks, this is really helpful! my initial thought is to accrue to DL also, especially since I want to redeem upgrades/tickets primarily on the long hauls to the US (I can stand miserable short flights to China)

right now I fly mostly CX to China and mostly *A to the US, so I end up with splitting my miles. *A is strong with Asia but is not so great with China (Air China's PEK hub is inconvenient because I am flying in from the South). ST seems like it might solve my problem with both good US and good Chinese partners.

I'm not that familiar with DL, is the redemption really that bad? if I accrue to DL, is it very difficult to get partner awards (i.e. starnet blocking like *A)? Conversely, any one have experience on how hard is it to spend CZ/MU miles on DL tickets?