[@ArenaSnow] I'd recommend the Hegemonia City-States mod for Rome I or, failing that, the Wrath of Sparta DLC for Rome II; both in the time period, and both give a good idea of 'troop choice' etc.

Oh, and read this: http://www.history.com/topics/ancient-history/peloponnesian-war

Gives a pretty good overall, and non-academic, overview of the whole shebang.

So, so far we've got claims on either Sparta/Athens aaaand barbaric Thrake...good, good.