Similar to the notion that people appear smarter when they wear glasses, displaying books in any room adds the perfect touch of sophistication. Placement and color of the books is key. Forget alphabetical order–like sizes should be grouped together if on a shelf to create the most streamline effect. If on a table, stack largest to smallest.
If you have a very distinct color scheme in the room, try to stay within that palette. If the books you wish to use are all the wrong colors, try removing their covers or redressing them in matching wrapping paper. If the books will be displayed on a shelf try turning them so the pages face forward.