The Spartacus War by Barry Strauss
This is what history should be -- short, concise, and no long digressions on the history of sandals or the archaeological significance of potsherds. When Strauss discusses motivations of various figures, he tells us what ancient sources said, what modern scholars think, his own view, and he makes clear that this is all speculation. Likewise, if the record is unclear about where or when an event took place, he gives the evidence and lays out the most likely answers -- but, again, he lets the reader know that this is conjecture.
After reading far too many histories where the author makes sweeping claims as though stating facts instead of speculation, this was a nice breath of fresh air.