The photo below is my suggestion for colour of floor. Furniture should be darker - similar to below. For the rug - choose one colour from the artwork and find a similar coloured rug. Don't put a mantle over the fireplace - it could be a health hazard - bumps and bruises. Blinds - unless you want them to make a statement I think white - to match window frames would be fine.

I would vote for the top example here. Itr gives an earthy tone to the room and yet is still bright and wont show every piece of dust or food.

I’d go with timber or cork. Cork is great in a kitchen. Easy on your feet and joints and things are much less likely to break if you drop them. Especially as you age, tiles cause fatigue if you are standing in the kitchen for too long. Cork is now available in lots of different colours and styles including charcoals and greys that might compliment your slate. It’s not all 80s orange. Of course timber can look great too. Just make sure it’s ok for kitchen use.

Hi Kieren, a rich, cool sand colour might work. Avoid yellow undertones. I think you’re right to stay away from anything too dark. Or try a pale beige textured rug. Added bonus, it’d be easy to find. A rug that mixes something similar to your couches with a LITTLE bit of green and maybe a bit of blue could also look nice. Accent the room in mid blue too, maybe? Stay in proportion to the room, but go bigger rather than smaller with the rug. Rug retailers will usually lend you a rug so you can try before you buy, which can be useful and some will bring samples to your door. Good luck