I used to bike to work in Austin. All year round. The only time I dressed for the ride differently than I dressed for work was when it was raining, which fortunately doesn't happen that often in Texas :) I remember trying to get chain grease out of my hose at one point, so I must've done rides in hose. I know I rode in heels pretty often.

The trick to not being no sweatier than I'd be if I had taken the bus is to bike with the least amount of effort possible. I took advantage of gearing, I took advantage of gravity and momentum, and didn't get any real cardio workout out of my morning commute. And the trick to dealing with helmet head was have long hair and braid it for the ride or have short hair that benefits from a little gel for styling. I could refresh the gel with water on my fingers to combat the effects of the helmet.

I never did learn the trick to not scratching my shoes on my toe clips, and I really do like toe clips tied loosely for riding to use the upstroke for even effort while pedaling.

Unless I dressed in something non-washable, I'd ride home hell-bent for leather to get in some actual exercise each day.