Now I'd like to recommend the book I use most for figuring out what I can expect to see through my scope, or somebody else's:
This book doesn't have finder charts, like the other one, but it doesn't suffer for it. the descriptions given of the objects and how they appeared in different telescopes are wonderful. They give you a clear idea of what to expect. The descriptions do use astronomer terminology a bit more heavily than the other books. The terminology is pretty simple to learn for anyone with an interest in astronomy, and there's a guide in the book.
All the constellations are here in one volume. The sky is covered from Polaris down to the sky as far south as it can be seen from Flagstaff, Arizona.
The book is definitely geared more toward the "serious amateur" than the Night Sky Observer's Guide. It doesn't have breakouts of particularly interesting objects, nor does it have illustrations of any objects, except a few special cases. However, this also makes is smaller and lighter, and everything is in one volume. It is far more usable at night under the sky.
It covers telescope sizes from 60mm on up, but the focus is definitely on telescopes 8 inches (200mm) and larger. Though there is good coverage for 6" (150mm) scopes.