I'm lucky enough to have shower facilities where I work, so I wear clothes that keep my warm/cool/comfortable on the bike and change after a shower. In the winter I don't sweat enough to need to shower all the time, but spring and summer demand it.

I'm pretty sure those folks that commute in their suits have 1) short commutes, 2) few hills, and 3) bike lanes.

The only reason we have shower facilities is because a guy used to ride to work and would take a sponge bath in the restroom when he got to work. A higher-up thought a locker room and showers would be a good investment.