What aircraft is the NRT-BKK leg? The NRT-BKK leg is 7 hours, and if it's the JL 763, those things are MISERABLE... make the AA 767s look nice, the seats have super-wide armrests so unless you have a narrow tush, they are very tight, and the pitch is tight as well (SeatGuru lists 34" pitch, which isn't awful, but does not match my experience.)

(I'd also consider using AirAsia or Tiger for Bangkok (DMK, the old airport, probably) to HKT, and only ticketing as far as BKK on the major.)

What about saving money and doing AA coach? 31ABHJ are really, really good seats if you can snag one on one of the days you're going.

What about paid Premium Economy on CX? Likely cheaper than 1, pricier than 2, and intermediate in comfort, but fewer connections than 1 and miuch nicer on the short-haul leg. If the fares are good, of course -- if not it might be pricier than 1, and not worth considering.

All on the new seats, AFAICT, and a fairly comfortable 3-3-3. Status WILL get you into the extended legroom (bulkhead/exit) seats for free, although as of my last CX flight you will need to phone to get those seats.

Only if regular coach fills up; I've gotten more op-ups on CX than I have on AA, and I'm a mere PLT, but it's pretty rare.

Wimps. I've done it at least once and usually 2-4x a year most years for the past ten years, and it's not that bad. Honestly, the awfulness of the long-arse 767 leg from NRT kills a lot of the goodness of business class on the leg to Tokyo.

Ditto.