I'm also Asia based (PNH), and will hit UA Gold level in the next few weeks.

In addition to the mileage bonus and extra luggage allowance, etc., a key feature for me is lounge access to Star Alliance carrier lounges -- since I find myself spending a fair amount of time waiting in transit in airports, regardless of whether I'm flying to/from the US, Europe or other points in Asia (there aren't too many direct flights from PNH to anywhere). Of course, from NRT, YMMV.

I agree with the poster above that MH has the best Y product, but for me the other Star carriers (especially for SE Asia -- TG, SQ, etc.) and the corresponding inter-Asian awards pushed me towards UA. Again, though, ex-NRT YMMV.

- Michael