Sedum palmerii is a great one for loving crappy soil. It takes heavily alkaline limestone rocky on a steep grade in Central Texas. It made it through fine on 5" of rain during the big drought a few years back. It blooms here in february and is cold hardy to 0F. I never water it. I thnk it a real workforse of a plant. It spreads readily. I imagine there are many more exotic options available for Souther California.

I think stonecrop sedums might be a good alternative as well, a lot of them are ground covers that are hardy and have pretty flowers that bloom through late fall.

There seem to be several types; I have one that I think is called Coastal Gem which I got from my friend's mom up in Mendocino, CA, but these links talk about a bunch of other types that might work too.

http://www.organicgardening.com/learn-and-grow/sedum-growing-guide

http://www.finegardening.com/plantguide/genus/sedum.aspx

Good luck!

Look for Aptenia cordifolia or Lampranthus or Carpobrutus, two of a number of ice plants, which also come in different flowering colours.

There are low-growing sages that are also nice.