Thanks for all the input. Here's what we ended up with:
Wed 1 Dec 10 09:50 Canberra 10:45 Sydney QF704 19B, 19A
Wed 1 Dec 10 15:10 Sydney 09:50 Los Angeles QF011 55B, 55A
Wed 1 Dec 10 12:10 Los Angeles 13:40 San Francisco QF3217 9A, 9B
Sun 5 Dec 10 11:55 San Francisco 18:15 Chicago (O'Hare International) QF3127 9A, 9B
Thu 6 Jan 11 22:30 Los Angeles 08:10 (Sat) Sydney QF012 55J, 55K
Sat 8 Jan 11 15:20 Sydney 16:15 Canberra QF771 20B, 20A
Cost of $2500 pp and (at this stage, at least) on the A380...so I think we got a good deal (and if we didn't, I don't want to hear now that I've paid!

)
I’m booking ORD to JFK/LGA, IAD to TUS and TUS to LAX separately online. The first two will be on AA, but the last won’t, as I don't see the point of flying east to fly west when I can get a direct flight on another airline.
Thanks for all your help...much appreciated as always!