Star Alliance airlines United, Air Canada, Lufthansa and Swiss have ticket prices in the upper $300s and low $400s for Los Angeles LAX to Amsterdam AMS, Paris CDG and Rome FCO for travel from late October to about May 10, 2018.
Airline websites show ticket prices around $446 to $470 round trip, while Momondo.com ticket prices are as low as $394 to $426 round trip through online travel agency sites.
United Airlines TravelMerry.com LAX – AMS $394
Los Angeles LAX – Toronto YYZ – Amsterdam AMS – YYZ – LAX
United Airlines/Air Canada/Swiss
TravelMerry.com LAX – CDG $417.46 round trip
Los Angeles LAX – Montreal YUL – Paris CDG – Zurich ZRH – LAX
Sat Apr 7 – Sun Apr 15 (Google Flights link)
United Airlines codeshare Air Canada flights
Los Angeles LAX – Montreal YUL – Rome FCO – YUL – LAX