Julia Annas has produced a remarkable volume intended as a reader for introductory ancient philosophy classes. I'm using it in my class right now, and I'm finding it to be exactly what I was looking for.
An upper level ancient philosophy course should be more directed toward examining the whole of a philosopher's thought, and reading longer works in context with the entire philosopher's outlook is ideal in that environment. In an introductory course, however, students are taking philosophy for the first time, and the ancient philosophers are merely a means to learning philosophy for the first time. Focusing on issues is thus more important than getting the whole of a philosopher's thought down in every way.
This book presents six topics, with ancient philosophers' writings on the topics organized as a conversation. The six topics are (1) Fate and Freedom (which includes divine foreknowledge and the fixity of the future), (2) Reason and Emotion, (3) Knowledge, Belief, and Skepticism (including relativism), (4) Metaphysical Questions (including paradoxes, the Forms, cause/explanation, and time), (5) How Should You Live?, and (6) Society and the State.
In any given topic, you usually find Plato, Aristotle, the Stoics, and Epicurus, with some representation by the pre-Socratics, the Sophists, the Skeptics, the Neo-Platonists, and even Augustine and Boethius to round out topics not discussed as much by the ancients. You also will find those whose work is not widely recognized as philosophy but has a bearing on philosophy, including Homer, the Hippocratic school, an excerpt from one of the Maccabean books, and a short snippet of Jesus' Sermon on the Mount. The most prominent ancient Greek and Roman philosophers dominate, however, since this book is about them.
Annas comments after the readings, sometimes on a few readings at once and sometimes on each reading. Her comments are suggestive of possible interpretations of difficult texts and potential criticisms of arguments, and often they simply pull together themes throughout the works of a philosopher or throughout the unit among different philosophers. Most of the time they're helpful to introductory students without simply summarizing the readings and allowing them not to read the text itself. Much in the comments is for further thought, though some is just to bring out things that may not be clear.
As with any project like this, one might make different choices about which topics and readings to include and what to say in the comments, but Annas is one of the most prominent scholars of ancient philosophy today, and reading what she considers to be the most important material for an introductory course in ancient philosophy is certainly going to give someone a good understanding of what there is, even if another expert might have preferred other things included instead or in addition.
Overall, I highly recommend this book for those first approaching ancient philosophy, and I consider it an excellent textbook for an intro ancient philosophy course. I'm glad she put this together.