There has been some threads on this in the past, but I wouldn't have a clue where to look for them. Yes, routes to Asia can be more turbulent than others in part because all the flights between Asia and the US tend to depart at the same time. There's one big wave going and one big wave coming back. There's only 1000 feet of vertical sep required in the ocean, which means with all these planes stacked on top of each other on the same routes, there's little room to maneuver to avoid turbulence. That's why ATC appears inflexible.

Edited to add: There has been a recent change on these routes though where although it's not legal separation and ATC says "unable," they add something like, traffic at such and such ... deviation at pilot's discretion. I suspect this came from the injuries that have come about during turbulence on these routes.

[This message has been edited by letiole (edited 11-07-2002).]