I am sure you have completed your organization by now. I would love to see what you decided to do. My bedroom growing up had the slanted ceiling. Since I was the shortest in the family when we moved in, it was my room. I grew to being 5'9" so my dad put my desk & dresser against the shortest wall so that I would be sitting and not bang my head against it. Same with the bed, my feet were at the low ceiling end, so I had to be careful making my bed. But at least I wasn't constantly bumping into the ceiling. Turning it into a closet area is definitely a great idea. When I grew up and moved away my dad was doing watercolor painting so be bought a HUGE map/paper cabinet/dresser to put where my dresser and desk were. He also put shelves on the wall opposite the window but was perpendicular to the slanted ceiling.