Update 9:20am PT: Oneworld matching LAX-Spain fares in low $400s.
Delta and SkyTeam Alliance airlines have several cities in Spain on sale from about $430 round trip for flights from February to early June 2018.
Milan, Italy is $415 to $470 round trip February to early May 2018.
Air France ticket for Delta and Alitalia operated flights.
Los Angeles LAX – New York JFK – Milan MXP – JFK – LAX
Air France ticket for Delta and Air France operated flights.
Los Angeles LAX – Paris CDG – Madrid MAD – ATL – LAX
Many other cities in Spain are on sale:
Vigo VGO $457 (easy train ride to Portugal)
Ticket searches on Momondo.com indicate Oneworld Alliance, American, British Airways and Iberia are matching these fares.
Los Angeles LAX – Chicago ORD – London LHR – Palma, Majorca PMI – Madrid MAD – Boston BOS – LAX
$429.82 round trip Tue March 13 – Thu March 22