You asked about paint so paint a lighter grey with all white trim including doors. Your room will look so fresh and be uniform with the kitchen. Paint the shelves white but leave the mantel stained wood that way your stained wood will be an accent to the white.

I'm sure you are already planning to edit out non dinning room clutter. I don't know your style but a black table would look sharp.

You did not ask about lighting. You may decide to change out the lighting when everything else is done.

It looks like you are off to a good start.

I would paint all the trim and doors white, walls a lighter gray on same strip as kitchen (that way it will have the same undertone) or just ask them to make the kitchen paint 50% lighter for DR. Looks like you have 2 ceiling lights and a fan in there. Have 1 chandelier