are you sure about the nonstop to Beijing...? I just did that route last month and I think all NW's flights stop in Narita which is hot and stuffy( the elevator is a funny contraption)...my favorite is the placard adjacent to the up button that says "no Smorking"...your parents will have a great time...tell them to try the Japanese breakfast and see if you can book them upstairs although it is normally solely for Elites...fun journey!
MJW