Expanding the Greek colonial world sounds like a cool idea, so I thought I'd ask a question inspired by another thread.
I don't think it is unreasonable to posit that the Greeks would need to be able to collectively project force abroad to really do better than they did historically, especially so that they could displace the Phoenicians, Lydians, Thracian, or others.
So I was thinking of what would be the best PoD to create a "League of Greeks" - essentially a confederacy of Greek Leagues/Polities. I imagine the key members would have to be the Athenians, Boeotian, and Peloponnesian Leagues, maybe include Thessaly and Macedon swiftly afterwards.
Primarily a military confederacy, or an armed Greek UN, it would be an agreement not to war between leagues/members, or interfere internally (as short-sighted as that may be) in other Leagues affairs, and an agreement to establish new leagues that would have a representative if desired/petitioned (for establishing new regions to colonize for example).
It doesn't necessarily require a central location for authority, but instead any League member can call for a meeting of all the representatives, either to defend an area, or forcibly conquer an area to create a new League/Greek Polity.
Core Members
Athenian - (They'd be split up I imagine as a requirement of Sparta and Thebes to partake in the scheme, and I can imagine Athens could still win out).
Peloponessian League - Being allowed to show their skill in war abroad, AND force Athens to agree to loosen its hold on the Greek world (in some perceptions), and retain their own dominance over their world, I think it wouldn't been impossible to persuade them, even if they wouldn't agree with Athens often.
Boetian League - A useful counterweight to Athens and Sparta, they could arbitrate between the new members.
Now you'd have interesting circumstances - what is the recognised territory of the Athenians (Say Attica and the Cycledies), or Boetia (I can imagine some northwestern expansion is on the books), and what would the current Athenian Territories be devolved into - An Ionian League? Or something smaller? Would Sparta have to agree to surrender territory to an Elian League?
Potential (Mainland) Invitees
Macedonia
Thessaly
Anarcanian League,
Epirus.
So what to people think? It is possible - if so, how? (without relying on Philip of Macedon

) What would people expect the members to be - and where the Greeks could project power en-mass. (My first thought is Thrace, but that would require Macedonia).