And on to another one which seems more promising, Ideal Interactive Map, which is also a plugin and advertised here. This will be deployed iteratively.
i.e. countries will be added as I see fit.
Their support forum is at the wordpress codex, here.
Now I have it rendering, I have added some countries, now I need to know how to insert multiple maps. How to insert a key/legend? And what data goes on the wire?
The pop-up boxes can contain full HTML and click through.