I gotta side with gang showers for two and a half reasons.
1) When I am in the gym with a friend, its kinda nice to be able to continue conversation while showering instead of yelling at each other through a catacomb. For example, rico27 and I can share dirty jokes about hookers in a gang shower...but we can't in stalls.
2) I don't like small shower bins. I don't like not being able to see what's going on around me, and I don't like bumping into the walls when I wash my feet and my hair.
2.5) Those small bins often get moldy. Exponentially more nooks and crannies for mildew to grow, not to mention the plastic curtains. Its all annoying, get rid of it.
I gotta say, my gym does not have eye candy at all, so I'm not in favor of gang showers as an excuse to perv, wank, or grope.