I see it wasn't listed as one of your options, but have you considered DL? I understand that you couldn't open jaw the ticket, but you could do PHX-LAX-SYD all on one reservation. I have used AS miles twice to get to SYD in business (once during a "sale," so the ticket was 102,500 miles) and have been impressed by the DL product on this route. I find their seats to be comfortable and everyone has direct access to an aisle. My last trip I used miles to get to SYD and then purchased a separate RT Business Class ticket on LanChile (SYD-AKL), which gave me some more AS elite-qualifying miles.