I vote for hardwood or engineered wood through the whole space, including the kitchen. Opening the wall would be nice, but I suspect your appliances are arrayed along that wall? I'd paint the wall the same pale color as the living space, and hang a really big mirror on the wall if you can't open it. Then you open the wall visually, and reflect the light from the sliders back into the space. (I know...me and mirrors. They are great manipulators of space, particularly when you commit to making them big!)

I would say you have enough gray already, and with the floors you would be much better off with an ivory or off-white paint color. Gray has been terribly overused and is now a dead trend, even though not everyone is aware of that. By that I mean gray used to excess and with everything else in a gray/colorless range. It seems to be very easy to fall into that trap, but with off-white wall you'll be encouraged to introduce more warm, vital colors into your home. Your rug sounds a bit colorless also, but you won't know until you see it in situ. I would encourage you to think in terms of the whole color wheel, and using some warm colors to offset the cool to give your scheme more complexity and interest.

Your question is far too vague, Your photo didn't post. If you are adding onto a home or knocking down a wall.......WHATEVER, you also need a phot releative to you, your furnishings, your space.

what should I do on the wood floors? im doing white oak 5". should I do regular wood or quarter sawn?