I often work from this type of thing, but sometimes the drawing alone can be beautiful. Sometimes it's so nice to be able to sit and draw, I couldn't in the top one as I was on the street, but I think the sharper turns of the pencil on the page help convey the excitement and energy of the event in question.
Edit: Have started painting some of these with watercolour paints, with interesting results. Will update as time goes on.
Later: The top one of these is now very colourful - and even more vivid.