The train + flyaway bus is OK if you don’t mind the long time it’ll take. Renting a car is also a pain: you have to go the agency to pick it up, wait for them to fill up their computer screens, put up with their hard sell for additional insurance, etc. And when you get to LAX you have to drop it off, then wait for the rental agency shuttle to take you to your terminal.

I’d just take the door-to-door airport shuttle, or fly from SNA even if that means foregoing a non-stop flight. Unless the fare difference is so high that I’m happy to pay for the shuttle.

How much can you save with the rent vs. shuttle? Ten bucks?