How much money do you want to save? Banking on a systemwide upgrade to Australia is a recipe for disaster. Every single person on that flight, regardless of how elite they are, is going to want to not be in their sardine seat for 16 hours. (Whether they have the necessary means or points to upgrade is another story...). It is rarely <$5k in business when I’ve looked, so if you are comfortable with that, that is the best bet. Another creative solution is to fly to Japan (SWU pretty solid bet on that one), hang out for a bit there if you want, then fly to Australia which is often cheaper (usually <$2k on QF, MH, or JL) — total outlay is $2k cheaper and you get a trip to Japan thrown in.