I'm interested in political philosophy, and I was hoping to become rounded in Greek political theory and philosophy, in hopes of moving on to Roman political philosophy with a bit of context. My assumption is that ethics and political philosophy should be understood (if not taught) in conjunction with one another, so are there any suggested authors and/or specific titles that you can recommend me on these two subjects?
I'm currently reading Aristotle's Politics and have just finished Plato's The Republic.
Also: I've noticed that some of the more obscure(d) philosophers of Greek and Roman times survive only in fragmented form. Are these fragments worth reading?