Damnoen Saduak is around an hour drive from Bangkok and is one of the biggest and most popular ones. Take your time exploring, be patient and look for vendors more inside rather on the edges who try to sell you expensive souvenirs. The deeper you go the nicer locals you'll encounter too.
I tried many variations of dan bauk, from very simple ones to some with many ingredients. If good spices are added it's very tasty. Otherwise it might be a little bit flat.
Very big choice in menu, too big for some people behind us, but we didn't mind. Service is kind and quite quick, smoothies are delicious. We came by a few times in different times of a day and left always happy.