I've put a lot of information and photos up here in the last couple days. I'm not always this prolific, but I wanted to give you a good variety of things to think about. It's part of the no rules, no right or wrong ways of doing things that I really want to stress. You can have a powerful message in your work - or you might do something for the fun of it. Or for the beauty you can create.
Almost all my book art friends make fat books, or I should probably say thick books. Books that are so chock full of interesting interactive things that the books cannot close. They stand open - ajar. I absolutely love their work and think the fullness and richness of their books deserves a big cheer!
BUT - I'm a closed book kinda gal. I worked in that library too long! I want my books to sit neatly tucked into a bookshelf. Mostly looking very innocent. It isn't until you open them that you discover the secret life they have taken on. My friends laugh at how stubbornly I stick to this with my altered books. But, then I pack them up all the time and haul them around to shows and book talks. They hold up a lot better without things hanging off or out of them.
You may want to do both! Or you may have a preference. Do whatever feels right for you and remember you can change your mind any time.