I live in San Jose and to me, it isn't that bad. Considering I live on the East Side of San Jose and drive everywhere. Sure you'll see 'ghetto' parts of the city but nothing extremely bad ever happens. So, looking at safety, I have to say it's pretty good. However, the night life here isn't that great, but Santana Row is a great spot to hit up if you don't feel like driving to the city (San Francisco). As for cost of living here, it all depends on where you're going to pick because it will vary. If you choose the Silver Creek, Evergreen or Blossom Hill areas, those will be a little higher but affordable. Another thing is, you're not too far from the city and things such as Santa Cruz.
Now for living in SoCal, you can't really go wrong with any of those places. If I were to choose, I would probably go with Burbank,Glendale, LA.