The Color of Rock, by Sandra Cavallo Miller

I enjoyed this for the Grand Canyon setting and the explorations of the type of medical problems that happen there.  

The writing, characters, and plot kept me engaged, but it suffered a little from a  mismatch between expectations and reality.  In my library, it's in the fiction section.  But this is clearly a romance.  I felt a bit disappointed by the emphasis on romance and sex, when there were many other more interesting themes and events to explore in such a great setting.  

So if you're looking for/don't mind a romance, I think you'll really enjoy this.