I've mapped out my dream locations before as well. Very helpful in navigating or becoming lucid if you memorize the map (hey, I know where I am! Shazam! Lucid!). Though my map was more like a bunch of different scenes drawn in bubbles connected by lines and not a real map you would use in the waking world.

Aslo, things break down a bit if you do things like teleport etc... then the adventure is to find the connections between the place you teleport to in relation to the places you already know.