i agree - i always find it much easier to recover from jet lag on an overnighter. if you manage to get some sleep, the journey slips away and before you know it, you've arrived. IMHO on the night flight from LHR it's best to try eat before you get on the plane and get to sleep ASAP (ideally avoiding dinner but waking up for brunch)... so speaks a weary business traveller... but if you're on holiday you may want to throw caution to the wind and get a day flight and soak up as much of the free stuff as possible (but feel a lot more groggy when you arrive).