lurker question re: book durability

[jillily3g]

I was directed here after trying to post on the main list. [must try 
to keep topics straight...]

I would like to replace my many-times-lent hardcover copies of CoS 
and PoA that have sections falling out, yet what I see on the 
shelves appears to be just like what I have. Does anyone have any 
suggestions on durable copies? Do the paperbacks last just as well?
 
Beth