Longest flight I can remember going on was SVO-JFK-LAX. 20 Hours air time, 10 min ground time the plane never parked at the terminal at JFK, We never got off the plane. Just refueled. We were traveling as SA's (space avalible) and unexpectedly were up graded to First class. 20 hours on a plane is bad no matter where you are - but its a little better when you're in first
Needless to say, I'm not looking forward to returning to SVO on another 20 HOUR flight on a 767-300ER!