Thanks for your comments everyone. I will post the mclevel file at some point. I work on it a little bit each day. Right now I'm hollowing out a Very Large Cavern. It's pretty dull work. TNT is good stuff.
Here is the Very Large Cavern in its current state. I got bored of digging this out and did other things today. Looks pretty awesome just as it is:
A brief glimpse of daylight:
Another hallway. This was once a natural cave. Just around the corner are some of the most complex, non-semetrical decorations I've done...they don't photograph well, however (grin):
I'm thinking of using a sign system, where different colored cloth blocks have a defined meaning. 'Red' might mean 'Danger.' I haven't really decided what the rest would be. Some of these natural caves I'm finding are easy to get lost in. Other times they lead somewhere I've already been working on. Some of them need to be marked with "You will never get out!"
Torches: I am going to run out of these. There are other alternatives for light, though (shafts and lava).
Rock Block: I would love to have an infinite supply of the grey rock block. Sadly I don't.