I’ve never run across a nice, authoritative overview of PIE and its descendants for the layperson. All the work I’ve seen has been rather technical and eye-glazingly dull, unless you’re really into patterns of sound changes and reading long lists of reconstructed roots.
The Cambridge Encyclopedia of Language, edited by David Crystal, has a decent, short overview. A nice place to start, although I’m not sure it will tell you anything Wikipedia doesn’t.
I haven’t read it, but you might want to try The Horse, The Wheel, and Language by David W. Anthony (Princeton Univ. Press, 2007). Although I believe this book focuses on the speakers of PIE, and not its daughter languages. (Which tells me that it’s highly speculative, which is why I haven’t read it yet.)