some additional perspective that may or may not matter: one of my considerations re: biz class (or first for that matter) is the company! i've established some interesting, fun, and profitable relationships on the long flights to/from europe and see upgrading as a networking investment (got a nice contract out of my last LHR-->JFK flight). that means that being in biz class during AWAKE hours is most fruitful.

of course, i don't sleep well on planes to start with. if i'm tired enough to sleep, i can do it in coach, especially if not full. two days before a europe trip, i start stockpiling sleep .