China Airlines, with partner Vietnam Airlines, has round trip airfares from Los Angeles (LAX) to Hanoi (HAN) for $548 or to Ho Chi Minh City (SGN) for $544 RT This makes 1 stop in Taipei, Taiwan.
Departs LAX-HAN: Aug 21, 24, 29, 30; Sept 4-7, 12-14, 18-21, 25-28; Every Mon thru Thur in Oct; Nov 1, 2, 8, 15, 16;
Departs LAX-SGN: Aug 28-30; Every Mon-Thur in Sept and Oct; Nov 1-2, 7-8, 14-16
Returns LAX: 7-21 days after departure date, wide availability
Use the dates above and book it on Expedia .
My sample travel itineraries attached. One is for 10 days over Thanksgiving Holiday) to Hanoi. You will need a Visa to enter Vietnam.