For a somewhat dated read for an introductory/high-level survey of the state of CPU design up to 2001, I find [1] to be quite informative. Of course, having been written in the frequency scaling era some of the 'predictions' are way off the mark. Nevertheless, I find it a good resource for someone looking to get a bird's eye view of the 30+ years development in the field.

[1] http://www.ece.cmu.edu/~ece447/s13/lib/exe/fetch.php?media=0...