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Four years ago, I flew CX SFO-HKG-HAN, with Vietnam Airlines codeshare for the second leg, and then Vietnam Airlines HAN-DAD.
AA gave me no credit for any of this. Code share, my foot.
AS did. With the new AS account bonuses, it was enough for an AS saver award.

Seats and service on VN short flights, both international and domestic (HKG-HAN and HAN-DAD), were simple but generous and nice. The domestic, pure VN, non-codeshare HAN-DAD economy seats had typical US domestic first class leg room and width (minus the doubled arm rests). Cabins were immaculate. The codeshare VN-CX HKG-HAN was typical CX service. A pure VN international short flight, I'm not sure. See comments on www.airlinequality.com

I was impressed with Vietnam Airlines. They are a good partner match for CX while AA or AS are a bit lacking. They are not lavish with IFE's etc--but neither is their nation or their budget. (Their non-Vietnamese language skills may be lacking.) However, they more than make up for it with class, charm, friendliness, efficiency and style. Vietnam Airlines food was fine and better than anything AA or AS will ever serve, unlike the food in most restaurants in Vietnam, where msg never ceased to give me splitting headaches. IMO, Vietnamese food, done with quality and without msg is excellent. Just remember, people who eat the stuff also fit into áo dài's, etc. The stuff should be good for you.