>I've rarely had any luck mapping with graph paper. I find
>that I end up running off the edge, or not having room for
>multiple levels, or worse, the problem being that ROM areas
>are not constrained to a grid. That is, N-E-S-W doesn't bring
>you back to the same room you started in neccesarily.

I guess I'm lucky, since I'm ancient enough to have played the original Adventure and similar text games, and shortly after began playing the then new advanced version of Dungeons and Dragons. Both things gave me lots of practice with graph paper maps and taught me three basic things that might help.

1, don't be afraid to re-draw a map so it's easier to read and/or you have more room.

2, drawing with squares connected by lines works great. You can distinguish each box easily by a number or letter, and the lines can be any length. Most old school hint books that actually included maps used this method, even when the map was pretty straightforward. It's also something like a programming flowchart.

And finally 3, if you have a multilevel area it's often easiest to map each level separately, or at least note the up/down paths apart from the rest until you can best fit it into the rest.
(ex. the air above Galadon should be mapped apart from the city itself, but the upstairs rooms in Galadon shops can easily just be noted as an aside before squeezing them into the rest of the layout)

Yes, it's still a pain in the ass sometimes, but I'd think it's easier than writing a mapping program from scratch.