In accordance with your requirements, I'd take a closer look at SOG's offerings for a couple of reasons. First off, let me say that in this size range, and even bigger, assisted openers ARE legal in CA in general, but laws vary city to city. LA is pretty restrictive. SF a little less so. In any event, I recommend the SOG assists, especially the Flash series because the bayonet style clip is quite innocuous and barely noticeable, and none of the knife sticks out above it. All of the Spyderco models mentioned are quite visible above the pocket when clipped on. Secondly, because of the opening mechanism, these knives open quietly compared to the Kershaw line, and close easily one handed as well (something a little more awkward with the lock-back Spydies).
Please note- these recommendations are just given based on the traits you stated that you were looking for and I'm not stating that any of these companies/knives are "better" than one another. All of these companies and models are offer good quality/value and each knife has its own strengths and weaknesses. I'd recommend you go to a knife shop and actually handle the various models to see what you are comfortable with before you buy. Hope this helps,
Jon