Well, let me illustrate with some scribbling:
So initially I thought that we each had an uncontested peninsula that was somehow connected via a "hub" in the middle. Based on the location of Mardrien's capital (which I know definitively from borders), that would have put the center of the "hub" at Troll or a little bit the far side, with Jowy's Cap closer (maybe around the Sheep/Rice/Silver) and a speculated 4th off to the East.
Now the more I see, the less certain I am of that arrangement. Certainly the Northern, Sheela-na-gig landmass could be a Mardrien peninsula, and maybe Jowy has similar, but the open land between Mardrien & Jowy and the irregular peninsulas to the East suggest a much more "natural" map than the crafted regularity of PB28.
So the wavy line is the natural chokepoint and it's all flat, open terrain so the defensive spot is Troll. With CRE culture, that will control the whole area. The second city at Duneyrr is probably closer to Mardrien's capital as the crow flies (and highly likely to worry them with its ability to boat their capital), but is far from defensible for them. So my thinking is that grabbing both of these spots fast is how I secure the front. Pushing beyond there seems questionable based on what I know now, but if we don't find a near neighbour to the East, then I can push down South of Troll towards El Chupacabra and the Stone.
Current Settler will go to the Cow/Corn linking spot, and then cities 4 & 5 will go out here. Then a whole lot of backfill into the peninsula.
Also, until I saw that Island to the SE, I hadn't spotted anywhere that looked like it would not turn out to be part of the same landmass (or at least not someone else's landmass). Now Sailing has another use, and it bumps it up in priority. This also seems to be a map where GLH will shine, but I doubt I'll have the opportunity to pursue it this time due to tech path and other priorities.
Right now I'm actually hoping the the Copper is not at the pre-mined spot, since I'd rather be able to build some cheap Warriors and I really don't expect to need it for defense in the near future. War Chariots salted with a few Archers should be enough to keep me defended.
Tech path is Pottery then Sailing/Archery in some order - depending whether I think I need the
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or the $$.
I will probably revolt to Slavery straight away next turn; I can regain the turn on the Settler with a whip, and it gets me 2 extra Worker turns to connect the Horses and pave the route to city #3. I can also take an extra turn of scouting the island with the WB, since I won't need the Fish online that turn.