Agreed absolutely. I've just bought a DONE4 that includes the same JFK-HKG sector, and it was a no-brainer to take the brand spanking new 777 over the rusty old 747 (despite the upper deck, which isn't a consideration for you in F anyway... grr ). I've flown the CX 747 in north america a few times and I have no doubt the 777 in New F will be a much fresher experience. Plus, you don't have to stop in YVR in the middle of the night, and you get to depart during the day and enjoy the pleasures of First without falling asleep shortly after take-off.

As for QF short-haul business class flights, it's a matter of debate between 767s and 737s. 767s have a much bigger business cabin and arguably slightly better seat pitch(?). But they're often older. Personally I prefer the smaller, brighter 737s and the more attentive service which a smaller J class offers. But there are really no significant differences in terms of seating, IFE, dining, etc so just pick whatever schedules suit you best.

One other thought: you might wanna consider choosing qantas flights scheduled to offer lunch or dinner rather than just "refreshments". There's quite a big difference in service when the FAs have to play waiters. The Qantas website will tell you what dining you can expect -- just search their online timetable and click on each flight to see a pop-up window with the aircraft and meal options. Just a thought...