As far as keeping books organized, our house has built in shelves in the entrace cove, so one shelf is for library books - a stack for myself and a stack for the kids. DVD's stay near the TV in a pile, out of the reach of our youngest hands.
Kids are allowed a book or two in bed, but I hate having them in the car. With so many small feet climbing around I'm always afraid they'll get damaged, so I try to avoid letting the kids take library books on the road... They have plenty of their own that I dont mine having damaged (then they learn from their mistake that if they dont look where they put their feet, they may ruin something... and at lesat this way it doesnt cost us anything! I dont let them take their more 'expensive' books in the car either for this reason)
Every night books are gathered and dispersed dependig on where they belong. It also gives me a chance to weed through books they may not have much interest in, books we've already read and studied, and I put THOSE in a homemade cloth bag whch we use to take books out/return so we aren't using a ton of plastic bags. Then on our next trip I return those books and we check out more.