I would rather wait for the decent food over fast food because they are cheating and cutting corners some where maybe with half pre cooked food. I do like a good Thai restaurant and have never seen a Vietnamese restaurant. Thailand would get me as a tourist for their food.
Thailand is a food-lover's paradise. When I first got there I used to revel in just walking around and trying out new things even if I had no idea what it was. I thought it would be the same in Vietnam and went through the same process but to no avail. I think it has to do with the spices or something but to me, Vietnamese food just tastes very bland and of course they deep fry everything, which is something I try to avoid whenever possible anyway.