Colleen McCullough's the October Horse is a fine conclusion to her fall of the Roman Republic sequence, carrying on past Caesar's assassination to the victory of the Triumvirate - i.e. just about to the end of Shakespear's Julius Caesar. A pity, as I would have liked to read the next volume that would bridge the gap with I, Claudius, covering Antony and Cleopatra too.
Not so good was Thomas Harlan's the Dark Lord, billed as the conclusion of his Oath of Empire sequence. It managed to merge a "with one mighty bound" resolution and a more realistic messy, incomplete, compromised outcome, falling between two stools. There is also one blatant dangling plot thread which strongly implies sequels. A disappointment, as it was going quite nicely up to then - but this volume really seemed to have gotten out of hand.
A not recommended - Kevin Anderson's Hidden Empire. It looked borderline (first volume of N being a danger sign), but then so did Karl Schroeder's Permanence, which I liked, used a similar sort of scenario (two distinct human factions, various mysterious extant and extinct aliens). And it seemed to start out OK, though the economics of the mercantile human society seemed a bit implausible. But things soon went downhill - gas-giant planets that are being mined for hydrogen but which have breathable atmospheric layers just don't work chemically. And then the tired old "aliens want our women" plotline gets invoked. Verdict - avoid.