Many of us here are fans of The Teaching Company, which has a ton of first-class courses on tape dealing with ancient history. Years ago, I started with the History of Rome by Professor Garrett Fagan. Over the years I've so often wished he'd do a second course just on the leaders of Rome, since the initial course is more of an overview (albeit, excellent) of the millennium or so of Rome's history. He has! I just found his new series on Emperors of Rome, and already he's brought up some fascinating points I either didn't know or hadn't considered. So I wanted to recommend this course in particular, and the series in general! They have frequent sales at which you can get a series for, say, $35, but you can often find tapes on Ebay at half the price or less, if like me, you work on a budget or if your fave doesn't go on sale.

History of Ancient Rome

The Emperors of Rome

The Teaching Company