Start with Warm Greige on the walls. It is that easy middle ground between beige and gray, so the room feels grounded and relaxed without leaning too warm or too cool. In a living room, where you want people to settle in and stay a while, this is the color that does the quiet work, holding everything together and looking good in any light.
From there, Soft White on the trim and ceiling keeps things crisp and lets the greige read clean rather than muddy. Then bring in Charcoal Slate as your accent, just in small doses, to add a little weight and a modern edge. So: greige on the big walls, soft white framing the windows and doors, and charcoal in the details like a side table, frames, or pillows.