Well, here is what I'm going to do for starters.

Going to grab an old copy of the Dungeoneers Survival Guide for they have a great write up in there about creating the maps by hand and the world below ground regardless.

Then what I'm considering may be easiest is to create a batch of symbols already generated which fit that map style. In CC3 they can be resized, rotated and messed with.

Also I took a good look at the Forgotten Realms UnderDark map. They drew more regions with an explanation of distances travelled to locations and such. I'd like to get a little more detailed than that but I don't think its necessary to draw every single thing.

Glad to hear I'm not the only one interested in this type of thing. There is another discussion on the forums talking about Isometric drawings. Its in the neighborhood and is helpful to read.

JJ