A yellow legal pad is always in my bag. It's not quite a journal or a sketchbook. However it is a little of both and more. Perhaps it's a bridge between the two. It doesn't extract the confessions and observations that a journal might. It doesn't focus attention as a sketchbook might. But anything goes on the yellow pad. This should be true for the other books but the difference is the pad itself. Brainstorms burst better on a yellow pad and thoughts flow freely.