At least the fireplace sort of blend in the space.

It blends into the space, yes. But I would like to give it a facelift.

-- You have several things going on in this great room. White trim, hardwood floor, slate floor, 2 kinds of area rugs, white cabinets.

Introducing another finish for the fireplace would add more differences, so you should incorporate what you already have in there when updating your fireplace.

Face it with slate tiles and use an oak mantle. These would tie in 2 elements you already have in the space.

I was planning on putting the same tile as kitchen floor on fireplace but it only comes in 12 x 24 so I wasn't sure what layout to do as it is very small.

I also have white molding going around French doors right next to it, so I could also do a matching mantel in the same white over fireplace.

A third option (and easier) is to paint fireplace a deep gray like the Tile color and add the white crown mantel. The bottom ledge is seriously gross and I also thought about putting a custom cushion over it to mask it and to make a seating area. I don't plan on lighting the fireplace because I have toddlers and it's right next to the computer. I was going to clean it up, paint it black inside and put pretty candles in it (probably flame less for now with the kiddos...)

Another option is stacked slate stone. Another option is marble subway tile to match kitchen counter tops