“Fireplace Room” Project

Our parking lot and garage are at the back of our house, so our back door gets far more traffic than our front door.
The room that our back door opens into is a small add-on room off our kitchen. It isn’t exactly part of the kitchen, nor is it a separate room of it’s own since it is only separated from the kitchen by an archway. The room has a fireplace and so the name. It has rough pine trim the plan is to paint it white and install a window seat where the built in bookcase is. I haven’t made up mind what color the walls should be. Any suggestions?