I wear jeans in winter and bike shorts in summer. I have one pair of the Levi's 511 Commuter and I like them fine, but I have other jeans that also seem fine. The Commuters might last longer due to the reinforced crotch.
I am a fair-weather commuter in a dry climate and don't worry about wearing cotton. If I were in the PNW, it might be different.
__________________
Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."