Avianca has some excellent fares from Los Angeles (and seemingly only LAX) to Europe right now on their 787 Business Class.
There is no need to do an open-jaw (London or Barcelona) but you can if you like to. Dates seem to start in February and extend until summer.
I only go it to price out on avianca.com.
If you can manage to get a longer layover (or stopover I haven’t tried) make sure you explore Bogota for a few days. It’s a South American gem.