In general SOCAL airline bases tend to be somewhat senior at the top, but somewhat junior at the bottom since junior folks may not want to subject themselves to the high COL.
But LAX is also a popular base for commuters, plenty of flight options and no SFO flow. I've seen a lot of people actually move to LAS or RNO recently, to escape the taxes and politics; they just commute to LAX or maybe SFO.
Yes, OO is the regional for SOCAL, in addition to LAX you can drive to bases in PSP or SAN from LA and vice versa. With covid traffic you can probably sit reserve for any of those bases, anywhere in socal (that won't last though).