Originally Posted by
norse_aztec
BA does a very credible job on both JFK-LHR and LHR-DXB, CX is generally excellent, and RJ gets mixed reviews, so I would suggest BA and CX.
The BA JFK lounge is very good, especially considering that it's not a home airport, and the LHR transfer mess is somewhat mitigated by the fact that your transfer is T4>T4.
Cathay's C class should be significantly better than RJ's offering. Their lounges in HKG are superior.
See
http://www.flyertalk.com/forum/showthread.php?p=8090242 and the link inside the thread for further opinions and reports.
All very well and true, but assuming the OP is planning on using AA miles (AA Plat is their proflile suggest its'll be AA) then BA transatlantic is out of the question - Unless the OP flies JFK-YYZ-LHR-DXB. Eitherway AA->BA or BA->BA (if going via YYZ) is the best bet.
One could look at JFK-CDG-AMM-DXB but the second stopover doesn't outweigh the LHR transit.
As for the RUH-BKK, both will require a stopover either in AMM (RJ) or HKG (CX) looking at the downloadable OW timetable journey times are similar - bearing that in mind CX would of course be preferable.
Seating would be the intra-asia short-haul seats which are cradle type seats with ~45" pitch. The transit at HKG is, likely to be smoother although I have to say I have no experience of transittting in AMM.
Either way you are looking at an ~9hour flight in effectively a regional seat.