Above 50F degrees, I wear Nashbar Ragster II sandals. Really comfortable shoes! I may wear socks on some of those 50F mornings, but leave the socks off for the commute home. Oh, and by the way, I don't care when it rains when I'm wearing the sandals. Just keeps the feet nice and cool and feels good, too. If it's not a cold rain, that it.

Between 20F and 50F degrees, I wear mountain bike shoes by Specialized. They are lace-up style and look, to me, more like casual walking shoes than bikey shoes. They are very comfortable.

Below 20F degrees, I'll put on my leather work boots. No clips, but the pedals are the type with SPD clips on one side and platform on the other.