Delta
In this flight 2 adult tickets in premium economy from Detroit to Vienna, Austria $4,098 NOT PER PERSON but combined. The flight is round trip and about 18hr and 35min.
Air france
In this flight 2 adult tickets in premium economy from Detroit to Vienna, Austria $3,990 per person. The flight is 12hr long and round trip.
southwest
This flight is 2 adult tickets in premium economy with 2 stops. One in Chicago, Illinois and the second in Paris, France. It costs $2,536 per person.