I guess I'll find out on Thursday. I'll post how it goes here.
Apparently there is some difficulty with their online system at the moment so I put in a business class upgrade request on the phone. I decided not to request PE as well because I consider the quality of sleep in PE to be very similar to the quality of sleep in economy with a window to lean against. (But I welcome contrary views if people want to make them.)
An interesting aspect of all this is that the points earn on this flight (with 100% platinum bonus) is around 30,000 SYD-LAX-SYD plus 5 or 10K LAX-IAD-LAX (do you get bonus status points for QF codeshares run on AA planes?) which is pretty close to the PE upgrade cost of 45K for the SYD-LAX leg. If it weren't for the uncertainty about the request being granted, I'd say it looks like a very efficient way to fly and use points.