Since you're in SoCal, you probably don't need anything for the run. We don't tend to have much of a problem with wet runs most of the time. I scatter some straw in the bottom of mine though, because it makes it easier to rake out (I found that I was raking a lot of dirt out of the run, and with the straw I can rake out straw and leave the dirt behind). The chickens seem to like scratching around in it too.
Adorable coop!
Adorable coop!