I thought you were fine on the challenge (speaking both as a runner and observer), just thought it was a little busy. I would have cropped tighter to focus on the people waiting and the runners, because that is where the whole waiting story is.
I know the feeling.... I ran the St. Louis Marathon, and you reach a point where you think "isn't this thing over yet?" Good shot. great interaction between the crowd and the runners. The crowd provides great motivation! ! ! !