It's been pretty easy this year, actually. I booked for March 2010, starting in April 2009. I was able to get two F seats on the morning JFK-HKG flight and seats home two weeks later via SFO. I since changed it to depart via SFO on the outbound (leaving three days earlier than originally booked) and back on the non-stop flights.
Based on my experience checking BA.com (which seems to be 1 for 1 with the CX inventory that AA sees), seats opo up all the time and there is no way to predict it. Just yesterday, I was able to get us seats in F (had been in J) from SIN to HKG because they added 744 flights and was able to move us from HKG-CGK to HKG-DPS (also because a 744 was put on the DPS flight).
In my experience JFK and SFO are offering the best availability. I've seen nothing ex-LAX.