Adding color to a simple bookcase adds such 'wowfactor'. You can do it inexpensively without the mess of paint by using fabric attached with spray adhesive to foam core board cut to fit inside the bookcases. Then just replace the shelves.
** Love this closet. Would add more drawers instead of shelving. Seems to be about the right size. Might need a few more drawers, though, and less shelves and/or the tilt out hamper. New House master bedroom closet