I recently began a new world (try the seed "love". It's pretty darn awesome. giant desert, and awesome cliff formations), so I'm making my first main base right now.
Which is a huge wooden house by a bay. With two levels of basement, a large main floor, guest house and an upper story bedroom.
Currently, I have the main floor and the bottom basement (main crafting area) done.
And once I have enough cobblestone, I will make a giant bizzare castle in some weirdly shaped cliffs not too far away.
And whenever pistons are made, I will make my theif hideout in the nearby massive desert.
Internet Kraken said:
Prison.
The idea is to build a large complex with many cells, dark enough so that monsters can spawn in them. Of course, with the doors controlled by levers, they can't leave without me opening the cell for them. So I can just sit and laugh at the creepers as revenge for all the times they blew up my walls.
That looks like a dungeon I had planned for my castle (still planning. Need WAAAAAAY more cobblestone before I can do it. In fact I was originally gonna do that on my last world in a nether castle...that I never ended up making.