I tried to get 2 First or Raffles class tix on SQ from the east coast to China for next summer. I was very flexible in dates (up to 331 days out) and couldn't find anything. I then tried for my exact desired dates on MH and was able to get what I wanted in first class. Ended up booking Virgin Atlantic (via the Atlantic) in Upper Class Suites instead. It cost a few more miles, but they also had availablity on the exact dates I wanted. So I'd suggest trying SQ, but when you can't get it, book MH or VS instead.