Pillow room: don't spend money on couches or lounge chairs and buy a really nice movie screen. (This would be really fun for movie night, to just move all the living room furniture and bring out the pillows!
Wetrooms—a luxurious and clever idea for a small bathroom. Why not use the whole bathroom? Do away with the shower enclosures and have clean, beautifully-tiled, waterproof zen space in your bath for the same budget as sprucing up a shower and bathroom.