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. Easily changed when you change your decor.
Also on these boards
A white bookcase in the corner (maybe Ikea) with either a dark color or a mustard yellow used on the inside.