The Historical Atlas of Ancient Greece is a basic introductory book used in many schools and is very easy to read.

"Alexander the Great" by Lane-Fox is a highly interesting read and very rigorously researched. More technical (and I suspect somewhat outdated by now) is "The economic and social development of Early Greece" by Starr. In a similar vein "Greeks and Greek civilisation" by Burckhardt is very useful. If you want something quite funny but still very rigorous Dover's "Greek Homosexuality" is very good, but again bit old. But honestly, the best way to approach Greek history is to read the primary sources, people like Herodotus and Thucydides. Personally I would avoid Xenophon, simply because he is, in my opinion, a bit dull.