Thanks for your input everyone and particularly thanks to number_6 for the explanation of which order the upgrades are done. Makes sense. I'm with you, won't be taking Air China (what is the point of finally making QF Plat if you don't use the Sydney First Lounge??). No outright award seats available on dates we can do unfortunately so will go with our upgrade changes which hopefully should be pretty reasonable.
We did the AY round the world last year and I agree it was excellent value and great product & service. It's one reason we just can't bear the thought of economy to Europe ever again