I guess the 767 fleet is the most social for those of us at LHR WW who work on it, probably down to the routes (generally trips with whole days of downroute) and the size of the crew (small!).
Saying that though, the 767 pilots still have a go at us for not being as social as the short-haul crews down route lol. I guess when you are on WW LHR going east +10 hours to west -8 hours, by the time we get to dar es salaam or lusaka we just wanna chill a bit. I can still remember what those LCA 767 trips were like on short-haul! It was easy to get excited about cos it was always a bit of a treat, one sector out to the sun, 24 hours there, one sector back. When your living out of your suitcase on WW it's a bit harder to get excited about being away i guess.