I would only advise a couple of things differently. I would probably substitute going MEL-HKG and HKG-JFK on CX for going Narita on AA. It'll take a day longer (I think) and AA's F class is ok, but you'll get better service and more miles on CX.

As far as the US segments, you can certainly milk a ton more miles out of it - try downloading the AA timetable on pdf and looking at routes. I would actually avoid BOS-SFO if you can - they downgraded it last year and you're back on a 757 with mediocre seats without footrests (I'm actually flying it tomorrow myself and downgraded myself to an empty coach cabin). Try going out of JFK if you can to SFO on the 767s. Enjoy!