a) my desk faces the wall, for fewer visual distractions
I'm sitting here feeling stunned that anybody could ever want their desk facing a wall, as the implication (in terms of any "open plan" environment) is that their back is facing, well, nothing. IOW, somebody can walk up behind you unnoticed. Me personally, I hate that with a passion. I'd pay money to have my desk facing out with my back to the wall, just so nobody can walk up behind me.