The story of Cleopatra, her life and reign as pharaoh of Egypt, her affairs with Roman leaders Julius Caesar and Mark Anthony, her influence on Roman politics, and her flamboyant suicide, with attention paid not so much to the legend as the facts behind the drama, with some material suitable for most levels.
"Cleopatra of Egypt: From History to Myth," edited by Susan Walker and Peter Higgs, contains 11 essays on the changing images of Cleopatra and a catalogue of artifacts from an international exhibit on Cleopatra and her world.
Sally-Ann Ashton's 2008 contribution to the study of Cleopatra is part of Wiley-Blackwell's Ancient Lives series. As an archaeologist-classicist-Egyptologist Ashton competently reviews all the recent scholarship on Cleopatra and details the art and iconography of the Ptolemies. The final chapter tells what happened to the descendants of Cleopatra; the first chapter explains the problems facing researchers of Cleopatra, and the second describes the various categories of ancient historians of Cleopatra. There are lots of interesting anecdotes, but this is not an introduction to Cleopatra. It is a book for people interested in evidence for the Egyptian queen as Greek and Egyptian, ruler and goddess.
Diana Preston's work on Cleopatra is also about the love affair with Mark Antony and the history of the times, so it's not so focused as some of the other books on this list. A new reconstructed image of an unconventionally beautiful Cleopatra seems to have inspired the author to write this interesting popular history.