Availability is much worse than it was a year ago ... enough so that I am not sure A is worth it over D as wind up in D most of the time even with an A fare. Few routes still offer first class, some airlines (such as BA) sell out due to giving F for J price, and the premium routes such as SYD-JFK or JFK-HKG are restricted to 10% of the cabin for A inventory. Being flexible in dates helps tremendously, if you can tolerate a slippage of a day or 2 or a different routing you can always find space though maybe not 2 on the same flight. A further complication is that as planes have been reconfigured to eliminate an F cabin some routes that offer F are no longer booking it months ahead just in case the planes are redeployed and the F seats disappear (this seems to be the CX case, they aren't sure of availability so don't sell it -- while a year ago this never happened, you could book a year ahead).