Remember only AA flight numbers for the challenge; also no Platinum bonus on JL flight nos. (or BA in a couple of months.)

SFO-HKG-SYD-SFO would net you around 42,500 net miles in J, 47K in F; SFO-HKG-NRT-MEL-SYD-SFO around 47K and 53K respectively, and something like SFO-LAX-NRT-HKG-SIN-SYD-AKL-LAX-SFO would net 48K and 53K respectively. Note there are some flights (e.g. QF NRT-SYD) that don't necessarily offer F, so just the 25% class of service bonus on those rather than 50% on flights with F.