For flights to US & Japan, Alaskan is good (Qantas, Cathay, Korean etc), or American for 1World. For Star Alliance, Avianca or Argean. All have regular bonus offers where you can purchase miles for ~US1.5c/mile. If you want to fly cattle class, no FF schemes are really good value for international flights, although AA can be good for Aus domestic, but I only fly business now, & they can be really good value. If you are relying on upgrades, be aware that discounted economy tickets are usually ineligible. Also, upgrades come from the same buckets as normal awards, and most airlines won't confirm upgrades until very close to the flight. The general rule is if you want an upgrade, be prepared to fly in the class you paid for. Personally, I jump on awards as soon as they are released, usually around 330 days in advance.