I don't buy books because I don't like to own a lot of things, so the books I have are either gifts or ones I would actually use a lot (because I also rarely re-read books). Any of the novels on my bookshelf are ones I haven't read because I'm less likely to read a book if I don't have a deadline like I do when I get them from the library. The only exceptions to this are My Antonia and Waterlily, both of which I have read. There are a few anthologies on my shelves too that include some writing I've submitted and had published.
My bookshelves are almost chaos; definitely not picture worthy at the moment. I have 3 tall ones in my foyer that aren't too bad; but DS's train table lives in front of them along with a bin of stuffed animals. The kid's main bookshelf is truly chaos. But hey they read em! The school fiction one isn't too bad either I guess. The one that houses our school stuff is controlled chaos. I have bins of school stuff on the floor in front of it. Maybe in daylight I'll think they look photo acceptable.
When we were house hunting for the move to New Jersey from Connecticut lo these many years ago Himself saw one house that had a two story library, complete with a rolling ladder. The house was meh. I asked him what they wanted for just the library.
These are gardening books in my study. When we moved here a friend came and stayed with us for several days and made them for me. Himself has (mostly) engineering books in his. There are three bookcases in the living room, one bookcase in the kitchen for cookbooks, three more bookcases on the lower landing of the stairs to the basement, a set of shelves at the bottom of the stairs for paperback science fiction. And oh yes, three more bookcases upstairs in the guest room.