I'm thinking of doing a small or medium world, with section outs. For general work flow, I'll finish the main world map first, then start working on the rest. I'm not sure if I'll animate the the main map (though I'm damned tempted to) just due to my facination with little sparkly bits of water and smoke from volcanoes etc.
On a technical scale, I think I'll probably make the map, divide it into a 4x4 grid, then make a bunch of grey-scale plasma fractals each of about 1024x1024. Massage the hell out of them so they actually represent the scenary in the ascii map, raising mountains, flattening plains and giving it an actual coastline shape. Join them all back up again and smooth the joints between them so there's no huge map edge drop-offs/rises. Then run it all through Fractint's 3d projection visualizer with a basic texture map and see if it comes up looking anything like the source ascii map. Massage fractals again until it does.
Then save the projection all as one layer and go pixel painting in PSP. Probably with about 3 or 4 different layers, one terrain, one terrain features, one for annotations, one for animated segments. Then open up legends, look for anything that catches my eye, mainly for "here be dragons" annotations as well as having a vague idea of cities etc.
Then I'll look at doing some cut-outs for more localized areas. Maybe. Just making a 4096x4096 map takes a while, but I'll see how it works out.