I've never been to Burma and you probably have more experience in Thailand than I do. I was in Laos a couple of years ago and again this spring. Although I was working and never got to see the sights (which I gather are mostly temples), I would go back just to mingle with the people and visit the villages. Laos is a very laid back and relaxed country, maybe too much so for some. The food is great, and so are the people. I don't know what the public transportation is like.