I've been having a lot of fun figuring out how to get map data into Blender in a way I like. I've been using QGIS to get data into a map so everything is layered nicely and georeferenced, then exporting elevation data, color (like rendered map) and maybe other choice bits of data as separate images so I treat them as textures in Blender. Then apply the elevation as real 3D heights, and use the other textures in the shader and get a 3D map!
Here is a view of Oregon, colored with USGS land cover data (based on aggregated Landsat data, I think) and elevation provided by NASA
