A dark blue would be nice, but whatever color you choose be sure to create a connection (don’t suggest wallpaper as the room’s configuration may make it feel too broken up). Suggest using art and a simple rug that doesn’t take away from the stone.

A distressed black finish could work well.

You could do a two tone color scheme

if you like the traditional white trims that you already have in the room, I'd keep it white and add wallpaper. You have plenty of natural light so you could go really dramatic with a wallpaper.

I personally would choose a Taupe color for the built in, and paint all the trims the same, with brass/gold hardware. There are so many great wallpapers, and a dining room is the perfect room to do something different than the rest of the home.

Thank you for your detailed input. Any Ideas for a deeper color?

You could do a dark green or sage green with similar sage green wallpaper in small print to match the farmhouse table.

SW Ripe Olive

I'd narrow the built-in to a smoky navy or deep olive, then choose the stone before committing to paint. A warm, creamy stone could tie either color to the farmhouse table without making everything match. For wallpaper, I'd keep the pattern small and low-contrast above the wainscoting so it doesn't compete with the shelving. Try large painted sample boards beside the actual stone in daylight and with your chandelier on—dark blues can shift a lot.