Air Canada is putting flights from California to Melbourne, Australia on sale, starting at $497 round-trip from either SFO or LAX to Melbourne (airport code: MEL). There is currently availability in February and March 2018.
You can earn 18,558 United Premier Qualifying Miles (PQM) if you credit this flight to your United account, which will get you almost to silver status (though you’ll still need to meet the spend minimum, which is easiest to do with United Chase credit card).
To book this trip, use Google Flights to find dates and then book through CheapOAir. Air Canada and Expedia are repricing at $857, so I have a feeling this deal won’t last!