I think one of the important parts of Coles's book (in the context of a course examining texts) is the simple value he places on stories. Not only the personal/'true' stories of his patients but the novels read by young polio victims.
I think it's also interesting (at this point in the course) to ask (again) why write books at all, why read them and why write nonfiction in particular. Is that even what is being written? The major difference I have arrived at in regard to non-fiction is treatment by the audience. I don't know how the quantify it. There's an assumed level of relevance to non-fictional books where as fictional forms need translation, analysis, theory.
Skloot's for example is connected intimately in many ways to our physical and ethical (social, historical...lets not keep going!) worlds. But as Coles (and his wife and her students) prove, so is Jane Austen. It's interesting that there's a value placed on literature "Even if I had known of a novel with a polio victim of his age, sex, and background as the hero, I would not have mentioned it at the time. His complaint went deeper, like Job, he was puzzled in the most profound way possible and wanted to find his own voice, make his own plea, his own cry.. p37"
The Call of Stories does a good job of showing how victims, students, and even the narrator (who connects to William Carlos Williams) can connect literature to their experiences. The 'use-value' of narrative is that it helps individuals. Books are 'sign posts' (68) but so then, can a painting  or a song . In examining non-fiction we've discussed several times the issue of non-socks but maybe what also bears consideration is the narratives that surround us with no benefit of a cover page. We've looked at film and some articles but even that doesn't really examine the breadth of narrative as implied by Coles. Life is narrative. We are surrounded by it, surround ourselves with it and our impulse to call it 'non fiction' or 'factual' is an interesting but perhaps as distancing as our efforts to call patients 'hysteric' and 'phobic'.