In May 2013 we flew from JFK to Hong Kong on Cathay Pacific. We used reward points to pay for Premium Economy seating.
We believe Premium Economy is the best value on the long flights. We were treated like business class and first class passengers on other airlines.
Marriott reward packages are a great deal although you must be careful that you move enough points into the airlines frequent flyer partner. Asia Miles.
Be careful with the conversion rates between Marriott Reward Points and the Marco Polo points.
If you are on the east coast the 12 hour distance requires you to call after 9 pm to talk to the "regular" staff. We had an incorrect points issue and kept calling and talking to the overnight staff who were unable to resolve the issue.
You will enjoy the flight.