Of course, Island of the Colourblind
. Out of print now, but Amazon's got 13 copies. Combines Sacks' compelling narrative style with an in-depth examination of how genetics, culture and environment, come together in what was once one of the more remote corners of the world. Of course, anything by Sacks is engaging and interesting, but "Island" is by far the better of his longer works. "Awakenings" was written long before Sacks came into his own as a writer, and tends to be dry and terminology-ridden. Definitely not as accessible as his later works.
As for other non-fic, Sacks is only author I read religiously; any other non-fic selections fall into the "looks interesting" category. Recently purchased (on Friday) from Coles was "DNA" by James Watson, which appears to be an illustrated guide to the history of the discovery of the double helix. (Says a lot for how low I've sunk on the "free time to burn" scale, when a science book purchase has pictures, eh? ;D) Can't find a link for it on Chapters or Amazon, but I bought it at the Coles in Square One, and there were several copies, so a Coles near you is likely to have them in stock. (Can't find a website for them, either.) I'll let you know what it's like.
Sad to say, it's my first non-fiction purchase that hasn't been a computer- or IT-related book since circa 1998. And meanwhile, the "to be read" pile grows ever-higher.....