Hmm, ATM I have two:
One is a bog standard two story house with a bed, furnace, storage and a workbench. Probably 9x9, made of cobble with wood floor and a glass roof. This is so bland because it is really close to a large Graeco-Roman temple on the top of a hill, with smooth stone, wool, cobble and mossy cobble all used in it's construction for the 'frescoes', roof, columns etc. etc.. Inside is a portal to the Nether and also a massive torch covered back wall. Underneath the temple is a little 'hellish room' with lava flows and burning Netherrack.
My other house is a three story, luxurious house, with a large fancy basement with a mini museum (stands for iron, diamond and gold blocks and a cake), a large store room joined on to it by a passage, a mezzanine floor overlooking my living room with a bedroom on it. In the living room is some carpet art, titled 'Red vs Blue' it is a 4x4 square with two edges blue of different hues and two red edges of different hues. In the middle is two purple blocks and two grey blocks (guess what that's from). On the roof is a little swimming pool with a diving board and a boat.
Oh yeah, the whole thing is floating off the side of a cliff, joined to the mainland by a 5 across bridge: the basement floor and walls are made of glass.
I guess it shows that I am taking Classics and History for GCSE, I like building relatively unorthadoxly and always think of defence first (the temple and house are both well lit, with safe rooms and only one real way in).