The palette
Blue commands here, so let it: a wide light blue for the bay, cut by the white lines of the causeways. Keep the mainland a dense pale grey grid with very little green, and save the green for Key Biscayne and the golf courses on the island, where it means something. Treat the port as frank geometry, quays and basins at right angles, like a piece brought in from elsewhere. That is exactly what it is, and letting it look softer than the natural shoreline would be the one real mistake available here.