Late to the party, but Metadept: Have you heard of http://www.random.org/ ? You could use its features to generate completely random noise for the terrain generator to work with.
I Want terrain like this, just platforms with large drops and lava at the bottom maybe. that way, you could become the best parkour/terrain navigator of all
Personally I think it should be Canyons Has occasional cave on side sharp top sharp to straight bottom Valley Smooth rounded top rounded bottom sharp side
I love this and i do not think the sharpness is a problem actually i feel in some cases rounded would be nice but the having a sudden drop would be really nice make me go back and cut down that lone desert tree so i can try and build a bridge or make me graple down one side them back up the other.
I would be nice to get rid of unsupported dirt/rock bricks being cheap bridges and actually make players build over terrain like this.
POSSIBLE SOLUTION: As for not knowing how deep it is, why not let the "underground wind" sound play if the cave penetrates that layer?