heh, both are essential, i think, although citow’s book is becoming increasingly outdated. (the info is still good, but there’s new stuff that’s not in the book.)
for something readable, get rengachary. you’re going to need citow at some point, too, but it’s not very readable and probably only useful when you’ve got some neurosurgery under your belt. (it’s quite dense.) there’s a lesser known board review book by moore and psarros (the definitive neurological surgery board review) that is much more readable. you may find that this is the book you’re looking for.
sorry, this post wasn’t very helpful.
the operative neurosurgery atlas mentioned above (caputy/fossett) is great, as well.
one thing i found useful was to leaf through these books in the bookstore or library to get a sense as to whether they’d be helpful for me or not.