Normally get what I request (Biz to F) when flying from NY or LAX. HKG - Syd hasn't been too much of a problem.
I do try and be a little flexible and will plan around availability if I have the luxury.
HOWEVER. i am flying BA to LHR and back as I can't take the risk of not having the flat bed. (I can't waitlist without having a seat booked , and they generally catch the double bookings on the same day for BA/QF)

Also managed to get a discount eceonomy to Biz X 2 for late September, but that was panning about 3 plus months in advance.

Am very happy with the option to burn points to get some sleep on the o/nite flights.