Re: ULMF Minecraft Server (Address can be found on first post)
There is an ocean biome to the east of the hill town, just past Bart and Oni's Blocky arena (with awesome 7 section displays!). I've already got the start of a tower there that goes down to bedrock, but doesn't break the surface yet. It was going to be a cool lone spire thing, but if people would rather build in the water, that's fine too.
I have just looked at the plains Rule found, and they're pretty expansive, as Dragon said, there's also a village nearby as well. I don't have a preference over where the tower town is built myself, but if you did want to do floating islands, I can do that too. But like Rule said, that would limit heights.