Today's model was a long, lean, older male with nice muscles and even nicer bones. The poses did little for me, though, until we got the first long one (25 minutes) and I requested a pose from the back. I had realized that he never turned his back to us - and (as I explained to him) I find the back difficult and would love a chance to try drawing his. He said he didn't care for his back, and that was why he didn't usually use it in poses.
Au contraire, I think he has a long, elegant back, and his muscles and bones were even better there than in frontal views. I did the best drawing of my evening. Fascinating vertebrae and hip shadows. Click on the image for a much larger view.