I think it could be really amazing for some of your really big maps if you could walk into a room and go "whoa, that's a seriously detailed map" and then get handed the magnifier and go even deeper. Even if you only had super-resolution data for some of the big features stitched in.

A raw piece of imagesetter film behind glass or acrylic and in front of a white background would probably look pretty cool (great contrast), although you'd have some mechanical challenges getting it mounted without bubbles. It may require a fairly thick piece of glass to get enough pressure in the center, and it may require a bezel so you can clamp/glue it to the backing securely.