In the spring, fall and summer, I wear lycra and other cycling specific clothes and carry my work clothes (shoes will be left at work). (I'm a sweater, no, not the wool kind, so I can't ride in my work clothes.)
In the winter, I switched bikes, wear winter boots, winter pants (with or without a base layer depending on the temp), light shell, base layer (and mid layer if cold enough), and, since my winter pants are sort of a chino-style pant (with a built-in lining for extra warmth), I will wear them as my work pants and carry a shirt. My winter route is shorter and I ride it with less haste so that I won't need to shower.