I like your use of a simple colored material to bring out key elements (I plan to imitate it ;-) ), but I think your examples suffer from being too busy and having too many unique and irrelevant details.
E.g. I'd suggest using the same (simple, preferably asymmetrical) spline in each example so the reader isn't trying to figure out what was done to what in each case. (Note that I need to follow this advice better in my own book. I only started being more consistent when I got to modifiers.)