We just flew back from Europe on 777 as we started the flight I believe the Captain or someone in the cockpit made an announcement we would be flying at about 32,000 ft to conserve fuel (most of the time we were between 32-34,000 ft). We never really seemed to get up and out of the cloud formations with some exception, but encountered a lot of turbulance for the entire flight with the all the crew being sat down for one period. My question is does it require more fuel to fly at 39,000 or would you expect there to be just as turbulant. I'm not an expert at this, but when we have had turbulence at lower altitudes we have gone to 39,000 for what seemed to be a smoother experience... why would they have not give that a go on this flight? We had some 100 mph head winds, but we were about 1/2 early getting into ATL and from about NYC south we moved to about 38,000... any experts out there to help me understand this?