I have my three Billy Bookcases in a row. It saves room and it actually creates the illusion that I have more space than I do. This is great for small rooms, like my library. Also, it makes a nice background for my videos and makes me feel very scholarly, which motivates me to do work.
I hope that my shelves provided some inspiration for you! There are great resources out there for how to organize your shelves and StumbleUpon and Pinterest are good places to go to for bookish inspiration. Happy shelving!