adaliabooks: It's not something I've looked at, but I imagine it would be a little more complicated than squares without a huge amount of benefit (you'd still get quite unnatural looking maps).
ddickinson: I can see your point. Probably a silly suggestion, but then I know nothing about game design. :-)
Any suggestions are fine, it wasn't something I'd considered yet. The ideal situation (and my original plan) was to use a system similar to that in Crusader Kings 2. The problem is I'm not entirely sure what that system is. I had a look at the modding guides for the game and what they seem to do is take a 2d map with the regions coloured in block colours and use that to create the regions, the borders, calculate where clicks have landed etc.
I tried this approach to start with, and it was reasonably successful (I managed to turn the image into a texture of the borders for my model, and read the clicks properly) but it was getting unmanageable and crashing because it needed too much memory. If I had a better idea what I was doing I could probably make it work, but I'm just fumbling around really...
ddickinson: but then I know nothing about game design. :-)
To be honest... neither do I :D
But it's amazing what you can learn on the internet if you're determined enough.
I just wish all my ideas weren't ridiculously complicated....