I think it would be cool to pick two complimentary colors (one for you and one for him) and paint two walls with each color. Then it would be a good division of spaces. You will probably want a television in the room that both of you would be able to view. Lighting is also very important. Also, consider close space. It is easy to store fabrics in some beautiful furniture/bookcases but computer equipment can be an eyesore so you may want to make sure he has hideaway storage. Post pix when you are done.