I just made it to UA Premier again after a few years of either DL silver or statuslessness.
About 7 years ago I was getting bumped up to biz on UA's transpac flights, but I doubt that would happen now. They also aren't flying from KIX as much as before.
Since most of my flights are from Asia, the domestic upgrades don't mean much to me. And with the Continental Onepass (soon to become UA Explorer) the baggage bonus is a wash.
Since the awards for Skyteam have shot up in cost over the last year, especially in Asia, and Oneworld is pretty weak here, I will probably stay with *A.
I do wonder whether a jump to ANA would be worth it though.