Now this topic I like:
This is a pretty hard question for me to answer. My answer would be biased because it would be based more on personal experience using the books I have read from my childhood to now rather than how current the content is.
1) The Sky Observers Guide - A Golden Guide : This was one of those little pocket guide books, about 168 pages or so. My (first) copy of this was for Christmas as a stocking stuffer. This book was the original book that got me hooked onto astronomy as a kid. My older brother was already into astronomy with another golden guide book "The Stars" from years previous. This book, though very outdated by today's standards, none the less, describes binoculars, telescopes, how to observe, basic techniques and individual chapters on Planets, Meteors & Comets, Stars & Clusters, Nebulae and Galaxies. It basically is an astronomy 101 course for someone on the street and also has star maps charting objects down to 6th magnitude. This is to me what Galileo's refractor was to him. It's an invaluable start that is easy to understand.
2) A Guide to Backyard Astronomy: This book was given to me at Christams in 2003 by my older brother. If the Sky Observer's Guide was Galileo's refractor...this is an upgrade to the Hubble ST. Chock full of Star Charts broken down into individual constellation, objects as faint as magnitude 12 were marked. The best part about this book is that all the pictures were from ground based amateur photos. Not hubble shots. What you see in the pictures is actually similar to the view through the eyepiece (your own eyepiece). This was the book that rekindled my childhood interest. Shortly after receiving this book I bought a new telescope, a 6" reflector.
3 Philip's Atlas of the Universe : This book is merely a reference text (unlike the other aforementioned books which are learning texts). The information is good and although somewhat inaccurate at times. Distances to certain objects are wrong (sometimes by 10% or more). Not that's it's any big deal. This is most likely due to the fact that the copy I own is from 2000. Technological advances in figuring distances to DSO's has dramatically changed I am sure. The author, Sir Patrick Moore is also very biased in his opinions (not only when describing what equipment to use but also in describing some stellar objects he finds as boring or not worthwhile...) STill, all-in-all a very good reference text.
4) The Planets : Simply eye candy. More of a pictoral encyclopedia with some technical text (a short paragraph) on each page. This book is simply the most beautiful and best pictures from space telescopes and robotic missions. From the Hubble to space probes around the planets themselves (like Casinni) to the Mars Rovers, every picture could be a full size poster in their exquisite detail. ALL of the major moons of Jupiter, Saturn, Uranus and Neptune (even Mars' moons too) have technical specs (diameters, mass, AU from the sun, distance from planet ect...) as well as the 10 brightest comets and the 10 largest asteroids all in incredibly detailed Hubble pics
5) A Pictoral Guide to The Universe: Same as above except it covers DSO's as well as the planets.
To sum up: I am sure that there are far more up to date books out there than what I have listed here. The reason I have chosen these books is simple. There are 2 books for learning (basic and advanced), 1 is a complete reference book and the last 2 are strictly for showing the most beautiful vistas of the heavens ever compiled. How much more of a complete library (in 5 books) can one ask for?