I read about the idea of staging bookshelves a while back, somewhere on line. Sorry I don't remember where so I can't give credit. I already did this with some of my bookshelves, but I never thought about doing it with all of them. My armoire with the garden books was a place I like to decorate and I didn't have enough books to fill all the shelves so I enjoyed staging it.
The article I read challenged me with the idea that books lined up like little soldiers was kind of boring and that your shelves could be more interesting by stacking books on their sides and adding accessories. I've seen decorator shows where the shelves are all about decorating and have little to do with a book collection, but this was different.
I have a ton of books and never have enough bookshelves so I wasn't going to do something that mean I had books left over, but I decided to give it a try. I found that I could actually get more books on my shelves. When you stack up your books you can usually get more in. Granted it's hard to get out the ones on the bottom of the stack, so you might not want to do this with books you are using frequently.
The other nice thing about it was that I could stack and group the books by author or category. That meant that I wouldn't always have things in alphabetical order, but grouping like books together works for me most of the time.
As far as accessories it is a good place to use those small things that don't really show up on a table top unless you have a whole collection. I've used everything from small pillows to birdhouses, cup and mugs with pictures on them, small figurines. You can also prop up small books so that you see the cover or just leave a spot bare.
It is a little more cluttered looking, so you may have to edit if it's not pleasing.