DONEx will be cheaper than a Business cClass ticket.

Make sure your SEA-LAX or SFO flight is on AA rather than AS metal. AA on AS is not eligible for DONEx tickets (you might have to go via DFW ). QF may be able to get you on YVR-SFO (or is it LAX?).

Sort your award flight for your wife first. Then match the flights through your DONEx ticket. Just give the airlines the PNR of both reservations so you can be linked in the process (otherwise you might be sitting away from each other and any changes to flights may only affect one of you).

CX BNE-HKG (IIRC) is Regional Business CLass whereas SYD-HKG is the full monty International Business Class (which is what you really want).

D class sometimes is zeroed out when the airlines know they can sell full J. That means some Fridays (etc) are problematic.