I want to go to Xian, Bangkok, and Siem Reap for a trip next year. I have US miles, currently enough for C, though I could buy more to get F.

I am trying to decide the best carriers to use. I think I might get a seperate flight from either Shangai or Beijing to Xian. Also, I would consider just buying a ticket on Bangkok Air from BKK to Siem Reap (but I think SQ might get me directly to Sieam Reap, and SQ, I know, is good.)


UA would take me pretty easily to China and Bangkok, but I don't think they have the best biz/first class.

Any ideas? I'm looking for a really great premium class experience.