I believe the best value for points is going Business Class from Sydney to LA on the a330 with Virgin Australia. The business class is the absolute best on the airbus. I believe it's 92k each way.
The problem is that regardless of what date I put its impossible to use my points to book a seat even picking the furthest dates in advance, am I missing something?
Is there a better point to dollar ratio for a flight?
Slightly different, but I did an upgrade on a BNE - LAX flight around this time last year. When trying to narrow down the dates, I actually found the call centre more helpful than the booking website. They were able to provide me with real-time availability over the phone to ensure I could book in economy, then immediately upgrade both myself and muffinwoman.
I'm sure there are others with much more knowledge than me who will provide some valuable advice, but if you have a rough idea of preferred dates it could be worth giving Velocity a call to see if there's anything available.