My wife and I took the full 16 night tour starting in Hanoi and finishing in Saigon (Ho Chi Minh City) with an extra on our own at either end (March 5 to 22, 2012).
We flew from Vancouver to Hanoi with China Airlines. Just one word of warning: bring your own food! Just think solid like a rock blue scrambled eggs - and they were probably among the better food.
I will not go into any detail about all the things we did and all the excursions because they have been very well described elsewhere. I'd rather concentrate on the aspects of the trip that reflect AMA Waterways.