Right now I'm building a Mansion in the sky. I'm not sure what to do with it exactly because right now it's more of a building with big open spaces, and I'm not sure how to do the roof. I also have a big open floating field in the back that will be turned into a greenhouse for Sugar Cane, Trees, and Cacti. After that I'm going to build a roller coaster on the side of the building that will go into an underwater city that I'm going to build. I'm also going to build a town around the floating mansion and later a crystal cavern (err... Diamond Cavern I guess) that you can only get through via the Nether. Basically I just want to build an entire world with interesting things in it that I thought up and built on my own.