Are built-ins an option? would look great with shelves to the right.. or a chunkier wood mantle across the full length? I’m not sure your style- from the pretty chair maybe transitional? I’ll attach some pics for inspiration. I love the first one.

This is one of the few times I might suggest an accent color for the fireplace wall. As it is now the wall just look washed out. Also, the hearth and the built-in seat are competing. They aren't quite the same height and the upholstery on the seat is kinda like the top of the hearth and kinda isn't.

Please don't do an accent color on the fireplace! It's fine the way it is.

The #1 easiest thing you can do to make it more interesting and fill up the negative space below the shelf is by add a trailing plant. I love a Swiss cheese plant in a cute little chalky black or grey planter for this. They are so easy to take care of and they don't need sun or water too often. Plus, adding some organic element is key to a perfectly styled space!

Second thing I would do is find a small abstract oil painting to add some color and lean on the shelf. A couple of small coordinating vintage vases or rustic/brass candles sticks and you are in business!

Lastly, add one more smaller pillow in a color to bring it full circle.

That's my recipe!

Aim to connect the entire area (decision on how to will depend on your interest and budget). If it were me, I’d definitely remove bench as it‘s the biggest hurdle in achieving balance, flow and a more modern look,

Take time to consider different versions and look on line for ideas/inspiration and shelving placement is key as well.

You might look at just placing a lovely piece of artwork over the mantle and then you should be done.

The A-Frame · More Info

The original picture shows too many levels of horizontal lines - the hearth, the bench, the top of the fireplace, and the mantle. The eye needs to flow and to rest.

The hearth and a mantle should extend all the way across, as in Maureen’s bottom photo.

It's been a while since you posted your pictures and don't know if you've done anything but here are my suggestions...