I think this really depends on your budget. You may be able to do something freestanding but you will be able to maximize the space if you can do a custom closet.

Maybe a closet on each side of the window with a bench seat under the window.

Is the ceiling fan necessary? Attic rooms like this usually have a fairly low ceiling and the fan makes it seem even lower. Does the room go clear thru the house? If you followed Harding's advice with double closets at each end it would allow adequate hanging space. The bench seat under the window could be charming.

Hi Nichelle --

The length of the room and size can help with a few options. Much of the wall space on the sides spear unfunctional due to the slope. If you have the room, I've carved out closet space on a sloped wall before. If you have enough width, you could put a closet as suggested by others on one or both sides of window. Another option is to just take one side and create a long narrow closet that's 5-6 feet. This will give you a functional wall and lots of storage. However it's really going to depend on the room size and what other functional needs you have of the room.

Check out this link from Young House Love. This couple bought two IKEA wardrobes and got creative: http://www.younghouselove.com/2008/02/over-our-heads/