Norwegian Airlines has Los Angeles nonstop routes on sale with LAX to Paris CDG $175 one way Nov-March and Paris CDG to LAX at $214 one way Nov-Feb or $238 in March 2018 for $389 round trip.
LAX to Barcelona BCN is $219 one way and Barcelona to LAX is $178 one way for $397 round trip.
Two one way tickets for an open-jaw Norwegian itinerary LAX-Paris/Barcelona-LAX is $353. One way flights between Paris and Barcelona are available for $20 to $50 with Ryanair, Transavia and Vueling.
Norwegian Airlines $389 round trip
Los Angeles LAX – Paris CDG – LAX
Norwegian Airlines $397 round trip
Los Angeles LAX – Barcelona BCN – LAX
Norwegian Airlines $353 round trip
Los Angeles LAX – Paris CDG/Barcelona BCN – LAX
Norwegian.com/us ticket price is $190.30 USD one way for Barcelona-LAX so $365 to book open-jaw round trip through Norwegian USA website. Lower prices are available when booking through a Norwegian European website.