First, you have to deal with the security boondoggle. Add 30 minutes for that, because you never know what you are going to get.
Because of how SFO was built and the fact that they can't use both runways simultaneously with even a hint of bad weather, good luck leaving on time. Pad at least 30 minutes to your destination arrival time to be safe (but I've had plenty of early morning flights get delayed an hour or two waiting for fog to lift).
And then when you get into LAX… good luck getting out. Add an hour just to get out of the airport traffic. Unless you want to go north, you are better off flying into SNA… but tickets into SNA cost $175.
On a good day you can do it in 3 hours. On a bad day it's 6. The cost is $50-$200, and it's always a stressful and shitty experience.
I just recently took the Amtrak all the way down. I took 12 hours and cost $93 for a business class ticket. Yeah, it took forever. But it was really pleasant. It just takes forever. It be nice to have something in-between.