I'm sure there would be some performers that your kids would enjoy. Specifically, I remember a magician/comedian and a woman doing lasso twirling tricks. The rope-twirler gave each child a turn and taught them what to do. My ds loved it (he was about 3 at the time). I'm sure there is even more - we just didn't spend a long time there because it was getting late.
One note though, there is not much activity during the day. A lot of the booths and things only open for the evening (I think around 4pm). However the restaurants and shops are open regular hours.