Now with two complete provinces i feel i have to reorganize my building strategy, as Tracia, with its 4 regions, appears to be best for unit production. I would welcome any hints from those more experienced with Macedon/hellenic on what to look for and build for it.
Macedonia/Thracia is pretty darn good, those are two great provinces. 3 resources, 2 wonders, and 4 of the 7 regions are ports.

Thracia would indeed seem a good province for unit production. I haven't played Macedon itself yet (increasingly becoming my choice for next campaign). So I'm not sure about specific tech tree production and barracks/unit idiosyncracies. During my Pontus experience, however, I can see in hindsight that I should have built pikes into my army composition much much earlier than I did. I didn't build any pikemen until the Level IV faction-unique unit...I'd definitely do it differently now. If you're new to Hellenic factions (as I am myself), check out Myth's pike/hoplite guide in the stickies...helped me tremendously.

As far as buildings, I assume Macedon gets Temple of Poseidon...spam this thing. Has zero food/squalor cost even at Level IV, and provides both food and public order. My "Hellenic standard" build for minor settlements is Field+Poseidon, it worked very well for Pontus.