I have a roll top desk and since it looks nice on the backside I floated it in my home office so I have a view of the entry and outside. I have a desktop computer on it and a whole lot of cubbies for office tools. I love it this way. I just turn around in my swivel chair to reach everything I need. added benefit of hiding all the paperwork on the desk from the entry view. You could do the same with your back to your bookcases. you dont' need a lot of room to walk on the window side. just enough to open and close the curtains leaving you more space on the door side. my office is 10'7"x11'8" so similar to yours. I worked on pay phones before retiring so have a lot of telephone memorabilia. you could hang your picture on the wall in front of the desk to see it when you are seated.
Q