Sean B. Carroll's Into the Jungle: Epic Adventures in the Search for Evolution is fantastic. I can't remember a time when I've read a science book so quickly or wanted to recommend it to so many readers (Dad would find it fascinating for the geology-biology connections, Mom would appreciate the human interest stories, my brother needs the biology background, the siblings-in-law [like me and all of my students] could benefit from the breadth of evolutionary thought presented, Sunflower Spinner should use it for her classes . . .). The book contains nine chapters, each about a major "adventure" in evolution, from the voyage of the Beagle to the finding of dinosaur eggs to the connections between genetics and evolution with sickle cell anemia. Each chapter is short, written as a personal story and contains enough evidence (including maps and scraps of original documentation) to explain the science. Because the book is designed as a supplement to an undergraduate non-majors biology text, the stories are all the same length with great documentation and annoying discussion questions at the end. The text book style works, however, as the constraints of format really make reading easy.
Having taken offense at another book blogger making fun of a scientist by equating "writes well for a scientist" to "writes well for a ninth grader", I paid close attention to the writing and, it's true, Carroll writes well for a scientist. He probably shouldn't have written about Darwin's "professional suicide" two pages in a row and there is an awful lot of seasickness and yellow fever going around, but altogether he writes well for a scientist, and, in my book, that's very well indeed.
I just checked Amazon and was pleased to see this book there (mine is a publisher's advance copy and it's being heavily promoted as a educational tool). Carroll's webpage points out that much of the same information is being used for a trade book, Remarkable Creatures. Certainly something would be gained in a book that wasn't written for undergraduates in class (or, as the first Amazon reviewer thought, for middle school science class), but it might also lose its concise focus and simplicity. I'll be interested to hear after you read either.