I'm a private pilot and part aircraft owner. I'm in a partnership with 3 aircraft (36 members total). It costs me a fixed $250/month plus ~$100/hr (fuel, maintenance etc). From San Diego I figure that LA, Sacramento, Phoenix, Las Vegas and the Bay Area are viable destinations (fuel and my own personal endurance).

Southwest at $240 rt to the Bay Area (full fare) is cheaper than the $350 it would cost me to fly myself to the SF Bay Area. The only time I've found it makes sense is to/from Las Vegas when I've got traveling companions.