Now that I've elected to be serious: a summary of the books that I've found most helpful.
From Alexander to Actium (Peter Green): Amazing summary of the Hellenistic era. There really is none better, especially not one so recent. Touches on all spheres of life, from economic to social to military (and of course political), with a great deal of philosophical and artistic discussion as well. Relatively inexpensive for the size and quality and timing of the writing, too, which I found to be additionally desirable. In addition, the large bibliographic and footnote section is invaluable for looking at sources on the era.
The Greeks in Bactria and India (W. W. Tarn): This was basically the first real book on Bactria to ever appear, and most of its content, despite being fifty years old and having to weather important discoveries such as the great city of Alexandria-Oxiana (at modern Ai Khanoum) and the revelation of the great Bactrian numismatic hoaxes with regards to the coinages of the Diodotoi, remains true. Here is not a discussion of military events, nor an exact chronology of life as it happened. While this is partly due to the paucity of the sources, and the heavy reliance on the inherently difficult to date numismatic evidence, it is also a function of Tarn's method: this was a history of one of the greatest undertakings in world history, the amazing experiment of Demetrius I, the Invincible, who resurrected most of the Mauryan Empire and added in eastern Iran as part of a great commonwealth of peoples, Iranian, Greek, and Indian, and its partial wreck by the agent of the Seleucid Empire, the xenophobic genius Eucratides. There are glorious heights here, but also depressing crashes; one is struck by that uniquely classical Greek capacity for unparalleled genius, but the similarly uniquely Greek capacity for vicious infighting, their inability to unite as a people, which resulted in their overrun by Rome in the West just as they slaughtered each other under the peaks of the Hindu Kush and were overrun by Saka and Yuezhi in the East. Tarn wrote with heavy analysis of most of his sources, especially the numismatic ones, and spends much time discussing ethnographic matters as well. It's an admirable work, pieced together from millennia-old coins, Chinese histories, archaeology, inaccurate (as Tarn goes out of his way to show) geographic texts, poems, inscriptions (in both towns and caves, as it happens), and finally the sadly insufficient Greek historical overviews. (Polybius writes of the Bactrians only when discussing Euthydemus and his struggle with Antiochus the Great, detailing the terrific Battle of the Arius River and the subsequent siege of Bactra itself; Justin, drawing on Trogus, has a few words to say of Eucratides. Neither of them was doing a work primarily on this subject and thus has few words to say, especially Justin, who was copying a book primarily for contextual purposes in his own history, and the digest of Trogus we get from him is not particularly interested in Bactria either.) The Greeks in Bactria and India is also excellent for its early discussion of the Seleucid-driven settlement by the Greeks of the East, a tremendous undertaking and one that altered the cultural map of the region for a thousand years.
The Peloponnesian War (Donald Kagan) - Though normally I would suggest reading the source text, in this case Thucydides, Kagan did a magisterial work on the subject, first in four parts (which I recommend), and then in a single-volume form, similar to Norwich's study on the Byzantine Empire. Thucydides, sadly, only covers up to the prelude to the Battle of Cyzicus, one of the seesaw turning points during the later stages of the war, and his successors (Xenophon being the best of these) were not up to his standard. So Kagan weaves together these sources with some more solid data - inscriptions, Socratic dialogues, Aristophanic plays, and the like - and gives critical analysis as he describes the historical events that take place. The Peloponnesian War, like the later wars of the Eucratids and Euthydemids, is one that bears witness to sunset on an empire, one which has a brilliant flash of light before the centuries-long twilight, namely that of Athens. So it would be remarkable even for that (a theme which, you may notice, has a particularly stirring effect on me), but Kagan also inserts a discussion of the politics and geopolitics of the time, and their comparisons to later (a theme he expanded on in On the Origins of War, a pretty damn good book even for those who don't agree with his politics). American similarities to Athens can sometimes be striking and somewhat frightening. Anyway, highly instructive, good read.
The Fall of the Roman Empire (Peter Heather) - There is probably no more misunderstood period in world history than that of the fall of Rome, specifically the Western half of that empire. I blame Gibbon and an instinctive dislike by many of Christianity, myself. But whatever the cause, Heather sums up what modern scholarship actually agrees on these days, instead of the bull that most often gets spit out in classrooms. Heather doesn't generally dawdle over military affairs, for partly the same reasons as Tarn: the ancients' descriptions of engagements and campaigns, especially in ill-documented periods such as the time of Bactria and the Fall of Rome, are notoriously lacking in military science and more descriptive of individual feats of valor and heroism. So for the most part, those nasty military bits get skipped over, and instead Heather looks to evidence in letters, inscriptions, histories, archaeology, and the like - you know the deal - to both debunk old myths and to construct a coherent narrative of events as modern historians of the period understand them. A large portion of the book is ethnographic, and still more on later Roman political theory, both of which make for interesting reads.
I lack the alertness or coherence to keep writing and talk about either of Goldsworthy's books that I particularly enjoy, namely Caesar and The Punic Wars. Maybe I'll do that later. They seem pretty self explanatory.