"How to add more drama and visual attractiveness to the fireplace and the walls ?"
Change the look of common areas at home is inevitable, but if we want to save as much money as possible, and avoid changing the materials of the fireplace.
think about painting the existing white walls a rich dark color, such as aubergine (eggplant bush). In a high burnish finish, that color will contrast in attractive manner with the white mantelpiece and really make it come out visually. It will add also a new dimension to the space.
Occupy the mantel with a grouping of decorative accessories to create a special centering point. Be sure not to fill all the mantel space.