Hmm, lookin' at this makes me want to try color sketches. But then you have to have a rather good concept of body proportions and what not, and I tend to use stock for reference anyways. Hmm...wonder if I could still try color sketching usin' the references?
I think the top three are my favs *nod*. In sketch form at least, cuz I know I loved the middle one on the bottom when it was finished.