I’m facing the same problems currently. Usually we are doing CAD-work in 3ds max for offline rendering, where I hardly ever use UVs (and am mostly relying on triplanar mapping and bevel shading).
But now we are trying to use CAD data in realtime applications, so I’m reducing them to around 100k - 500k faces (the STEP Import plugin for Blender makes this a lot easier already - 3ds max can’t go that low). Baking lightmaps or ambient occlusion is a must then, but with them consisting of so many objects, I’d have to rely on an automated unwrapping solution for most of them. Blender’s automatic unwrapping (smart UV) is already a lot better than what 3ds max has to offer out of the box, but as mentioned above, it produces some overlapping and flipped UVs (especially on mirrored instanced geometry). Also it splits up a lot of the smaller details into single polygon islands, which - once you add padding - wastes a lot of UV space.
I’d also be interested in better (automatic) unwrapping solutions that can deal with high polygon counts. Having this inside Blender would be a plus.