One book that comes to mind is Kamen's Road to Empire, which described the rise and decline of the Spanish Empire. It is a good read with a lot of good information and analysis, although throughout the book you have to put up with Kamen soapboxing his thesis that "see, 'Spain' wasn't homogeneous" and a stronger one that "Spain never did rise to be a true empire".

Overall I recommend it to those interested in the global empire that was Spain.

Another standout book is Elliott's Imperial Spain which covers the Trastamara and Habsburg periods, but more focused on Europe and the Meditteranean.