My family has a home library and we treat it like a regular library. My kids pull anything off the shelves they want, and read it, and then it goes in a box to be re-shelved (since otherwise some of the younger kids will put them back in semi-random places). They also have access to a huge CD library and a CD player/amplifier. The only rule there is they have one CD out of the case at a time (because they tend to drop cases of they are piled up). This is strictly a practical matter to limit the amount of repair work I have to do. I know the cases are replaceable; I've replaced many dozens of them and I"m sick of it!

There are also some "special collection" things: mineral collections, electronic kits, etc. The only rules with those is they have to be put away. They've got a low table, a high table, and couple of comfy chairs, and reading lamps.

We ask them not to read them while eating or drinking (other than water bottles) and to keep the library items downstairs. It's because we have toddlers who don't have access to the library and they like to tear up books. We also ask them not to fold over pages (in paperbacks this results in the pages eventually breaking off, sometimes shockingly soon due to acid paper becoming brittle). I ask them not to write in the books. We have a huge supply of yellow pads and other notebooks of various sizes and they are welcome to use them, and an endless supply of pencils and pens.

I make a distinction between honest wear and carelessness. I love it when I see the books showing wear from reading. A lot of the books are somewhat rare and were hard to obtain. They can read those just like the others. I do have a special collection of signed books upstairs in my bedroom but most of those books have "reading copy" mates in the library. I don't love it when I see that someone's left it upside down on a dirty floor and the spine is split or a cover has been torn off. That's not honest wear - someone let a toddler at one of the library books without supervision.