San Diego has fantastic running on trails, by the beach, track etc. and a ton of great local races. The weather is perfect and we have tons of hot girls who live here.
It's expensive and crowded because its a great place to be. Between LA and San Francisco is a vast wasteland that no one needs to visit for any reason.
Northern California is good for hipsters and snobs but the weather is worse.
All the other states are inferior in some way especially if you are a runner.