Something to remember going from GIS to a DCC app like MAX is that images are 100% fully loaded at render time (unlike GIS where it only loads and displays a subset of the data.) That means you often have to sacrifice quality to achieve a rendering. Luckily we can introduce a lot more detail through geometry.

Global Mapper is great because we need to produce meshes that are int he right coordinate space (.dxf) rather than the DEM importer in MAX that centers the DEM at 0,0,0.

It is a pain, but creating a tiled area and going through each tile and prepping it, applying the maps, etc. is just part of the job. You can speed up some of the labor using scripts, but it's still pretty manual.

Here's my workflow:

GIS layers into Global Mapper (images, DEM, etc)
Export terrain as .dxf
-Generally I'll use Global Mapper's built-in gridding to make smaller parcels
-Smaller parcels mean smaller polygon counts, and smaller images on each
Import .dxf into autocad
-3ds MAX does not handle real-world coordinates, so I use Acad to move things around in world-space
Translate to 0,0,0 (this translation is used for all data uniformly)
Save as .dwg
Import to MAX
Convert to Poly
Weld the verts in each parcel
Flip the faces
Apply a single smoothing group to remove faceting
**For terrain parcels that are far from the scene, I'll use Pro-Optimizer in 2009 to reduce the poly count to <1%0 of the original). I HIGHLY recommended down-rezing the terrain using this method rather than downsampling the grid resolution in a GIS package because of the averaging that GIS packages do can really do a number on your terrain data.

Then, to get the images, I'll add the original .dxf parcels into Global mapper and use thier bounds to generate the bitmaps (usually saved as 24 bit .pngs to avoid compression artifacts).

I then map those onto my parcels in MAX.

The other benefit to making a lot of tiles is that you can down-res the bitmaps for areas you won't be near. You can also apply different pro-optimizer settings as needed.