Perhaps it is just local pride, but nowhere I've been diving, nowhere in the world, compares with California. The abundance and variety of sea life you can encounter underwater from Carmel to Catalina is without compare. The cold water, however, takes some getting used to.
My solution for the last five years or so: the Whites Fusion Drysuit.
Representing a newer design idea in drysuit tech, Whites uses two shells: the first inner shell is basically a bag made of "DryCORE," a waterproof, airtight, very durable but very flexible material. The second shell is an over-suit of lycra and neoprene. The first shell holds air around your body and the over-suit squeezes it all down and keeps it streamlined.
The Fusion is easy to put on. You simply step into it and essentially roll it up your legs, and over your torso. The fit is fairly amazing and it is extremely comfortable, like a warm water 3mm wetsuit. There is no bulk and no heavy material to limit your movement. If you wear a really thick insulating layer with the suit, that can get in your way, but otherwise my movement in the suit is not constricted.
I highly recommend the Fourth Element Arctic undergarment for California. I had used an insulating layer that came with the drysuit, and it was not very good. Instead, I prefer the Fourth Element Arctic. It seems to cover our California temperature range perfectly, and does a brilliant job of keeping me warm. The Arctic also takes very little weight to sink. I find I'm diving with far less lead when I dive dry.
Seals and zippers with this suit are standard industry stuff, and made with the same quality you get with most other manufacturers. The seals are fairly field-replaceable if you have the spare and some glue with you. Whites also makes a whole series of easily swappable outer-suits. I've been diving the simplest and lightest "Sport" shell and love it. Pockets might be nice, but thus far I haven't seen a reason to upgrade.
While diving in a drysuit will keep you a lot warmer, the change in buoyancy takes some getting used to. There are certification courses for drysuit diving and the one-on-one advice you'll get in those sessions is invaluable. Finding yourself inverted with your legs full of air and fins poking above the surface is both scary and embarrassing. If you are in the San Francisco Bay or Monterey areas of California, or can get here from elsewhere for one-on-one sessions, I recommend calling Bamboo Reef.
Link: Whites Fusion Dry Suit