We just kept their board books/ easy reader / picture books on the lowest shelves. Paperbacks seemed to get warped and bent up sitting in baskets. It never stopped my toddlers (and even crawlers) from picking out books to look at. Just don't pack them do tight so they can move them around some and see the fronts. Although sometimes it did mean reshelving a whole bunch of books because they "read" them all. The nicer the book the farther up the shelves they are stored.
Library books are stored in a basket by the door and I check what's on the library cards online regularly so I know if one has gotten lost somewhere (usually in someones bed).
Sorry, I wasn't much help for new ideas! I have considered, but never had room for, one of those shelves that you can put books on flat so you can see the fronts. That would be great for toddlers and easy to reshelve.
