I try to ride with as little cotton as possible, except in summer, where I'm flexible. Wool trousers end up looking good after I ride in them. No one can tell I've been riding, as the wrinkles and sweat disappear quickly. They breathe well and are about as suitable for riding (for me) as cycling-specific clothing. I get really nice pairs of trousers, Italian made, at Costco for about $50 a pair. They wear out more quickly than normal because of the riding, but I think I get a very good value from them overall, since they fit two purposes. And I don't have to change when I arrive.

Last night, I rode in the rain, 7 miles each way. My trousers served me well, and they dried after I got to my destination the first ride. The second ride was wetter, but I arrived home and was able to change. I plan to put fenders on my bike, which will reduce the problem a lot. Even if you don't plan to change, it's a good idea to keep spare clothes at work, in case you get cold and wet.