Originally Posted by Ldnn1

The key benefit is there is a better lounge at JFK with full dinner if you fly a 'Sleeper Service', so you can eat first and get longer sleep onboard.

The other potential benefit is the possibility of upper deck seats on the 747. Alternatively as a couple you can get a pair of middle seats which are quite nice.

If you don't have status, these benefits are severely offset by the lack of free seat selection.

Going westbound, I would choose AA as the seat is much more spacious and onboard food better. Also the new CX lounge in T3 should be open by the time you fly in Dec/Jan and is likely to be very nice.