Alan,
I would prefer being able to pan by just holding down the mouse wheel button, but that is possible but clunky for other reasons. Moreover, the space bar is much easier to find than the option key which unless I put a piece of tape over it, is impossible to find. I always have to think about this option key, and moving through a drawing, I would much prefer to think about something else, like, say, my design...
I guess I would like the mouse to be able to do all the maneuvering through the drawing, and the keyboard commands to do all the drawing/modeling operations. Seems logical, time efficient and intuitive at the same time. It also frees up your non-mouse hand for keyboard commands, which, believe me, I do make much use of.
That's just my opinion, and I know we all approach programs differently.