I commute every day (no car), and one of the things that doing this implies is that you will be riding in the rain, in the dark, and will sometimes be carrying extra stuff with you. As a result, I think that any bike you consider should either have, or have the ability to add, lights, fenders and a rear rack. At 20 miles, you may want to use drop bars, but Santa Monica is pretty urban, and I prefer to be more upright when in urban traffic. One bike that you might consider is the Novarra Fusion from REI, which comes out of the box with everything that you would need for a commute:

Novara Fusion