My parent's have a house in Durango, Colorado with three tiny, sloped ceiling rooms on the third floor. My three year old picked one to stay in during our last trip and we had fun decorating it! I used a lot of Mouse + Magpie products, which I love!
It's a small room, so we used our space efficiently. We have under bed storage too, which is helpful for tight spaces. Isla loves this little room-away-from-home.
All sources cited on my post here.