I suppose it's also relevant to point out the each of us deal with jetlag differently. By way of example, 6a arrivals at HKG or LHR, followed by a shower plus a day at the office are fine we many, but I prefer evening arrivals myself. Sure, I get less sleep on the plane, but the hotel bed is more comfortable. The calculus for leisure trips is different (e.g. showing up at USM before noon is fine)..