In SoCal you might consider San Diego also. As others have alluded, if there's anywhere it's going to be warmer - it's there. Still 5/7 mil suit conditions though - at depth it often is colder. One of the most famous dives there is La Jolla Cove, there's also about a dozen other shore dives in that area. I know you said boat dives but diving from shore is easy (beach entries) and more affordable. It's also really good, in some areas you can get into the Kelp - often with a surface swim, there's sea lions that will "dive" with you, often Leopard sharks pool at the Marine Room site and even Scripps Pier is a decent dive since it's been there for decades.
www.divebums.com for more info.
There's a small fleet of dive boats based in the Mission Bay marinas. They dive locally at San Diego's wreck alley, to the Kelp forest located off Point Loma and to Mexico's Los Coronados islands all on 1/2 day/full day trips. Sometimes Coronados are 2 days. Also some of the boats regularly go to the Southern Channel Islands as mentioned above. It's also a reasonable drive to Dana Point to catch the Express over to Catalina on occasion. californiadiveboats.com - the bottom 6. Marissa is a good boat, Humboldt is a good boat as is Lois Ann. Islander and Horizon go south for multi-day Great White cage diving but non-season they're options also. Pretty luxurious by
local dive boat standards and obviously liveaboards.
To address the warm issue, once at Los Coronados I started diving in a 7/mil with 5mm jacket and hood. On the second dive, I left the hood and the jacket on the boat and was still warm enough that I unzipped some. And that was in October (due to the currents fall is often warmer than summer in areas of SoCal) The diving there is fairly shallow so I suspect that it warms more than other areas also.
I also dove that way at La Jolla Shores the next day but dropping down into the submarine canyon it was noticeably colder - I would not have wanted to stay down there very long. My buddy who was more cold sensitive was freezing and signaled he wanted to go up.
The next year we dove the Cove and a couple sites south and I still remember how warm it was. Unusually so from what another diver told me. I think the Channel Islands - being Islands - are more in the deeper water currents so tend to be colder. But that's just my speculation.
As everywhere else within view of the ocean, the farther inland the less expensive housing is. Although nowhere is cheap, i think the Clairemont/Clairemont Mesa area might be cheaper. So is El Cajon - IIRC it took us about 45mins. from there to Mission Beach once but we made the stupid mistake of arriving at Friday's rush hour. You might look around Escondido also - that should be close to an hour. I know a couple people with normal jobs and that's where they live.
As dizzi mentioned - one area to avoid is probably Imperial Beach due to the border crossing. It was seedy looking 20 years ago - once we turned around and noticed all the alley fences were topped with razor wire. My friend at the time was looking to buy there but not after that.
San Diego has the world famous Zoo, SeaWorld, the beach cities with the clubs etc. We've gone there as a group and hung out in Mission Beach, beach by day, bar-hopping at night. Also the downtown trolley makes that convenient and it goes to Tijuana IIRC. I also like the downtown waterfront at night - some nice restaurants and it's just pleasant. For more upscale things there's Coronado Island across the bridge. San Diego is very much a military town if you have any skills related to that when looking for work - big naval base off Coronado, another on the mainland side and Miramar (Top Gun) is up north inshore of La Jolla. Some wineries in the Temecula area also.
The downside for anywhere there is it's expensive.
hth,
