Personally, I was my pass with one hand on my side/waist so I can feel where they are, and the other hand bracing on my leg or tank (or grab bar when i had one) Most of the girls I've ridden with also kind of hold on to my hips with their knees too. Not enough to restrict my movement, but enough for me to know where they are and how they are moving.
No one seems to like the seat on the Buell however, no biggy as I usually have the "no ho" on it anyway.