This is a perfect spot to Showcase all the design principles of permaculture. It really depends on your climate zone but being in San Diego, you still have quite a bit of time to grow a whole bunch of different vegetables including root vegetables and leafy greens.
Option one would be to do kind of a square foot garden type method where you have different vegetables in zones but another option would be to plant a wide variety and see what takes foot and do something polyculture.
How about putting a dwarf citrus tree at the bottom center and then having things go around it so that in the future you can have some shade for the house and save on the electricity bill?
All in all I'm super jealous that you have such a great place to practice gardening and sharing the bounty with your local community and Neighbors.
I think I'll do a square foot style approach in one of the terraces, and then experiment with other methods in others. You're right - good way to experiment.
I would do the citrus tree, but the bottom area will likely be (sharp) succulents to prevent animals from running up the terraces!