This world is absolutely amazing.
Seed Code: 217
X: 219 / Y: 68 / Z: 9
This is a small-ish cave, with basic coal and iron. It joins on to other caves and would be a good cave to start with.
X: -306 / Y: 66 / Z: 61
This cave is much bigger - and I'm sure it has a lot of potential to supply your daily mining!
X: 14 / Y: 66 / Z: 366
[note: coordinates are taken from far side of island]
This island is my favourite. It has more sheep, chickens and even some cows! There is a huge ravine and plenty of impressive hills.
X: -9 / Y: 12 / Z: 448
This is a diamond vein of 2. It is behind a lava lake so good luck getting to it!