I am strongly recommending Amazing Arachnids by Jillian Cowles.
This book is in line to win the Greg Laden’s Blog Science Book of the Year.
It looks like a high quality, almost coffee table like, book on the arachnids, things like mites and spiders and such. But that is only what it appears to be on the surface. Just below the surface, it is a compendium of evolutionary amazingness, a detailed description of the photogenic history, behavioral biology, and co-evolution of plants and animals, with almost all the protagonists in the numerous loosely connected stories being one sort or another of amazing arachnid.
Geographically, the book focuses on the arid American Southwest. This allows the author to be quasi-comprehensive in coverage of species (about 300 from among 11 orders). It also allows the author to tell the story of these critters as a story, with interconnected features of evolution and ecology. This is literary hard core science, with great illustrations (about 750 color photos, and other illustrations).
Because of the US SW focus, it might be a better purchase for people living in just that area. But as is the case with a handful of other nature-oriented books, like the The New Neotropical Companion, the science content and overall interest of the book transcends geography. You’re not really going to want to get that close to these arachnids anyway….
This is a very good book. You will learn things, even if you already know a lot about arachnids.
The author is a clinical microbiologists and photographer.