I agree that seat blocking was a valuable perk for status customers. I always went for a window (on the 3 side) and looked forward to an empty middle so I could get some work done. I find this even easier to work from than up front, as you can put your bag/briefcase in the empty seat. On the 757, I prefer the 10A or 10F seat (with no underseat storage) so having B or E empty also gave you storage.