Have had a similar situation with a recent client- We saved on the stone/marble by creating a floating panel effect- creating a sense of lightness to the overall composition by not allowing the wall to touch the floor or ceiling (reduces any overpowering effect)-. Built in shelving to ceiling also helped integrate the design. We also placed the TV above the fireplace to reinforce the sense of symmetry and unified focal point- Art simply slides up with a gentle touch...No hearth seemed necessary...
Q