carlosMM:
I must admit I don't have experience with such a big map (I used to play huge and now large only), but just a few points that I want to make:
1. floodplains make great worker/settler factory. Looking at the map, there is no civ nearby on our landmass, so we can build a lot of cities. We need those floodplains, and need them immediately - the original dotmap requires a temple first to pull in those tiles. That's why I would like the red dot to be moved one tile to SW. Plus, which city we'd like to build Great Lighthouse? If it's the capital, we have to set up another settler factory asap (by whipping a granary as soon as possible).
2. When I need to make a choice between "two cities overlapping one or two tiles" and "no overlap but waste 2 good tiles", I usually go for the first, since IMHO shields are not so important once you reach size 12 (and with factory and power plants running), and using those two tiles may bring more benefit to Ancient and Middle Ages.