I do NYC-So.Cal a few times a year.

If going to LAX, United out of JFK is the best service in coach. Nice big 767's and usually some empty seats to strech out in.

If going to SNA CO's EWR-SNA service is the only nonstop out of the area and the service is not too bad. The drawback is your on a 737

Any other EWR-LAX service is on a 757, or 737
and if not in FC should be avoided.

I have had decent luck getting status upgrades even as a silver on CO into LAX & SNA , but it is a dice roll.

Off topic, but I can't understand why CO has not got any compitition on the NYC-SNA route.