I like the current brick, and would just repaint the wooden mantel/surround to a lighter tone, maybe not all the way to your white cabinets, but taupe or cream?

Agree withh acm. herringbone looks pretty. Maybe lighten up mantle.

Why is using the same kitchen tile not an option? While I agree the format might be too large for the fireplace, perhaps you can find a smaller herringbone in the same or similar material?

Something like this, then paint the mantle white:

Calacatta Gold Calcutta Marble 1x2 Herringbone Mosaic Tile Polished, 1 sheet · More Info

This is polished, but you will probably be able to find it honed, too.

The backsplash tile is still an option. I just thought it might be boring since its just a white subway tile. However, I am now thinking I like this herringbone idea and might even use the same white tile as the backsplash but change it to herringbone.

It sounds like you're creating a beautiful kitchen space! For the fireplace tile surround, a custom mosaic could offer a unique and artistic touch that complements your kitchen without feeling repetitive. Mosaic art allows for endless design possibilities, from subtle textures to bold patterns, and could enhance the elegance of the room. As for the floor, consider a neutral tone that harmonizes with both the mosaic and your Taj Mahal Quartzite, creating a cohesive flow throughout the space. Feel free to visit our page for inspiration—we have a wide variety of mosaic options that can truly transform your fireplace!

IMO paint the wood surround the same as the cabinets or at least tape a large poster board there to see if any othrer change is needed I do not think the marble mosaic is a great choice .BTW nothing is gained by posting pics that are not your spaces . So finish the kitchen post those pics and then get actual help.