If I say that I'm staying at LAX tonight, I mean an airport hotel, not in the airport itself, either inside a terminal, on the curb, or in their parking garage. I don't have access to the tarmac, so that's not an option. Is In-n-Out open all night?

To me, Los Angeles refers primarily to the downtown area and not Santa Monica, Pasadena, or even Westwood or Hollywood. Otherwise if I mean LA more generally, I would say something like the LA area. To me southern California starts around Santa Barbara and extends beyond San Diego to the border, as well as inland to Palm Springs up to the (state) border.