It looks like the SFO fares I saw were actually Aeromexico (not LA/AA/TAM), they're actually even less. Approx $1,800 a/i roundtrip on AM from SFO/LAX. If you schedule it right, you can catch the Aeromexico 787 between either LAX-MEX and/or MEX-EZE.

For my own trip I was able to snag LAX-JFK-GRU-AEP (nice mix of A321T, AA 77W and TAM A320 shorthaul biz), EZE-SCL-LAX (787-9, 1-stop in LIM) for just shy of $2100 on Orbitz. It had the best schedule combination for my specific needs plus I like AEP more than EZE, particularly for arrivals as the immigration queues are almost non-existent there and it's a short ride to my hotel. Also considered LAX-MIA-SCL-AEP for the outbound and even better schedule but opted to route via JFK for the A321T business class and extra EQP.

Great little trip.