Great idea quiltingcandy...and the doors on the closet. (I'm thinking double hinged ones not bi fold) could easily become a design wall using 2 vinyl backed table cloths (inexpensive).
It depends on how permanent the refit would be...if not wanting structural changes one could get adjustable wire shelving in 12 or 18" depths attaching the standards to the studs in the wall..or get short bookcases to fit under the slopes.
In a previous house I had a sewing room with sloping ceilings. The straight wall was less than 3' before sloping and was very claustrophobic for me...only had a small window which added to the closeness. Good luck...