Thanks to everyone for the input. I think I'm going to give CO a try.

I also agree that going through customs and immigration at LAX is to be avoided when possible, l was there a few weeks ago and it was seriously understaffed. I'd do it if there was a nonstop to EZE, but an hour wait at immigration and customs and then a terminal change at LAX for the short flight to SFO is the last thing you want after two segments and 15 hours.

From what I've seen over the past few years, I get the impression that we probably won't see a nonstop to EZE from the West Coast anytime soon. Maybe if AR decided to go EZE-LAX-(somewhere in Asia), perhaps as a codeshare with another carrier. A problem is that the transit visa requirement for non-US citizens makes it more appealing to go to Asia via Europe. Also, AR probably has bigger fish to fry right now.