What sort of feelings do you wish to show in this picture? What kind of day is it? Is it a busy happy day or just another day at the market? Think about what sort of feeling you want the user to feel and then its easier to pick the elements that fit. You have 9 windows and they are exactly the same, putting some shades at different heights would help a bit. Just sticking a thin shade behind the windows would be good enough. Some smoke puffing out of the chimneys would be good, would give the houses a more inhabited look. Picture looks pretty good.