So, I found a seed on the forums here that had a triple ravine (I only see a double ravine but the 2 ravines are stacked on top of each other going in different directions) and an abandoned mine in the lower ravine. I decided to build a base into the cliffside of the upper ravine and spent a good deal of time digging out the space and patching it up. The "base" has a nice glass ceiling and glass walls and part of it is even underneath the lake which you can look up in to. Right now, it's pretty much a blank canvas and I wanted to share it with others to see what they would build. There are a few chests in the base, but most of the supplies are up in the temporary "boat house" floating in the lake above including 4 full chests of cobblestone and 3 stacks of iron. There is redstone, gold, and likely diamond in the ravine below but I havent gone down to explore it much more than once.
The entrance to the base is a hatch to the left of the glass ceiling under a tree.
Soo.. here are the pics, and the world. If you use it and build something, post some pics to share!