Take a look at more of Timothy Schorre's sketchbooks here. I used to do lots more drawing in public places. It works really well when you are in a busy spot where everyone is paying attention to something else so you can look at them and the scene freely. Flickr is a good place to see lots of sketchbooks. I don't care for the "art journaling" groups. The sketchbooks there seem to be all about achieving some sort of effect with materials. I prefer the purely mark-making sketchbooks, or the ones like these that capture an ordinary moment.