I have a lot of books, most first editions, and over 200 childrens books, all hardback.
Volumes like "grimms fairy tales" collections and large collections like that, where they will publish those every few years I have a 4 inch thick volume in paperback for $12. Books like Andrew Loomis, who is out of print I have first printings that are on the 'top shelf' section of my library
Most 'readers', as I call em, are paperback and usually used. Also, I have 50+ refrence books from library sales/bargin book store bins just for the pictures. Those get all beat up and stuff.