I have a world I started and dropped 20 minutes later, left it there "in case one day I want a building challenge".
I renamed it Waterworld right after that, because the entire thing is ocean fucking everywhere, with a few tiny tiny islands here and there. Oh, and I think I found a big desert with nothing on it after sailing for ages.
If anyone wants to give that a shot I can grab the seed and post here.
After that I started a new world which is my current, spawn is in a big-ass swamp, and south of it there's an amazing desert with villages and an area with big-ass vertical cliffs and rivers with dark areas full of mobs in broad daylight and stuff. I really like this world.