From the Bay Area to Australia
As far as I know, United is the only airline with direct SFO to SYD flights. Virgin Australia and Qantas* fly out of LAX. Flights tend to leave in the late evening and arrive into Sydney in the early morning after crossing the international date line. SYD to PER flights depart every few hours. Flight time is a short 5 hours so all up you arrive in Perth around lunch time, 2 days after you left SF.
Qantas
Suggested route is SFO -> LAX -> SYD -> PER. Typically you leave SFO around 6pm and get a 11pm flight out of LAX. Qantas uses either 747s or the A380 depending on the day. You can sometimes go via BNE or MEL instead of SYD. The total time doesn’t vary much.
Virgin Australia
Similar to Qantas but uses 777ERs. Can connect via Sydney or Melbourne (slightly longer). You earn points on Virgin America, but probably not as many as you’d expect.