How Do You Take Your Bookshelves?

I'm currently doing some work for a client whose dining room walls are lined with bookshelves. She wants to wallpaper the room, but she doesn't want the wallpaper to be too busy with all of the books in the shelves. In her dining room, the books are the main feature, however, in some rooms the books are simply a piece of the larger scheme. 

In some shelves the books are all vertical, in some shelves they are horizontal, and in others there is a mix. Some shelves hold only books, and some shelves hold books, decorative objets, and even lamps. Some are color coordinated, others are random. With so many ways to style a shelf, there are dozens of ways to decorate around them - how do you like your bookshelves? 

 Photos courtesy of House Beautiful, Elle Decor, Traditional Home