Great game, some small suggestions

[Punch]

Oooh... 3D!

The maps already have the contour data, so essentially you already have a height field because you have your X,Y coordinates with a contour height that will give you a Z. You'd probably want a parser to take just that information and put it into a faster to load file, then you'd just set the vertices at the given heights. You could make a 3D representation of just the terrain with relative simplicity (relative... [;)])

Seriously. When you're filthy rich you should put this in.

Though it does raise issues about the units. Do you model each individual unit? We already have the data for each unit, but that would be a lot of guys and would take a lot of time to render each model. You could have a model for each tile, but since each tile represents multiple unit types this isn't really ideal. And then you start getting into how much animation etc. is required, which in turn requires new and better sound to complement the graphics. All this leads to loss of focus on the actual game design goals. You'd be better off staying with just tiles initially.

OK. I'll stop babbling about this [:'(] It would be a long time coming, but it's a funky idea. You need to win the lotto or something Dave [:D]

[Trigger Happy]

Bah, 3D and the operational level don't mix together rea;;y well... but that doesn't mean that making a 3D version of the map should be impossible. As you say, the maps already process all the coordinates X, Y, Z, so it should be simple to render it graphically. Ok, I'm not a programmer, but I experimented with some 3D mapping programs back in december, and it did not seem that complex.
max Z (X, Y) = white
min Z (X, Y) = black
from that it's pretty easy to make a 3d representation. Just put an overlay and voilà. Of course, not to be gamed on.

[Punch]

Yeah, as you say it would be fairly easy to make a 3D representation, but the gaming aspect of it is what would take time. If you just wanted a flyby or possibly a more interactive way to check out a unit's LOS then you could do that, but it would have to be seperate from the gameplay map.

As for the greyscale representations of a height field, in this case it would probably be just as easy to use the existing data format instead of generating an image file from the existing map and reading that at runtime. It would be far simpler to just create a text file with the heights that is updated every time the map is saved from the map maker.

This isn't really under serious consideration though. It's just a field of study that I'm interested in and currently working in at uni [;)]