I wear the shorts part of zip off leg lightweight nylon hiking pants over bike shorts.
I can't get myself to wear just the black lycra when touring...probably my imagination, but it seems harder to meet people when I just wear lycra

On top, wicking tee shirts. Synthetics for all other weather conditions as well.

We go on extended road trips by car and the only cotton I carry any more is a pair of blue jeans. I've even changed over to synthetic boxers (Undertech from Kmart.. 2 pairs for 12 bucks) and socks. So much lighter, cooler, less wrinkly, more compact, and easier to launder and dry. Some of the tees look and feel very much cotton.