I have a 12 x 20 attic room and if I had a choice i would like an adjoining storage room and a sewing room. 3 walls of shelves for fabric. 10 x 12 in storage room at least. In sewing room, space for sorting, sewing machine space, cutting table and ironing dresser. Also bookcases for books and tools. Plug in ceiling or floor so can place pieces in middle of room without having cords to trip on.Extra shelves for sorting and scrap bins that hold scraps cut to size. A bulliton board, a design wall. A comfy chair for reading , appliqueing. relaxing or visitors. Small sink and coffee pot optional.
What else would you like and what do you already have that needs to fit in.