The area to the left upon entering behind the French door would be great for storage (bookshelf/file cabinet) unless you want the door to open flat against the wall. Don't be afraid to put two desks in front of the large window facing the back yard. But he may want his desk facing the center of the room with chairs for clients opposite it. So your desk on the right (laundry side) facing out the window and his desk on the left facing into the room, and a credenza behind his desk in front of the window if the window isn't low to the floor. That would leave room for a bookcase/shelving on the bare wall from the laundry to the far window wall. Your desk could have a right-hand return coming along that wall also.

Light or not window treatments and glass desks may help keep the room feel open and bright. With lamps in the two far corners of the room. Wood file cabinets would feel richer/homier than metal. Also carpeted floor except for the path in front of the window where your chairs will be rolling, maybe a hard flooring.

really appreciate the insight!

project update