I use the library a lot for books to take on the road. Since my trips last 4-5 weeks, I helps some, but not enough. 2 or 3 hard covers is all I want to pack due to weight and space. I don't like to take the paperbacks from the library due to their fragility and the fact that they are not usually current.
I will order a newish book from the library - in SFO they will transport any book you want to a neighborhood branch, and then pick them up before I go. Internet renewal is wonderful. Usually, it is only the books that my wife cons me for that end up with fines. Still at $.10 a day, it is not so bad.
When I go to the Chicago area and stay a month, the Evanston library will issue a temporary card when presented with a letter from my hotel giving my length of stay.
In Switzerland, paperbacks cost Sfr 15.00 to 17.00. Reading for entertainment gets quite expensive when a book last only 2 days. I rationalize it as being cheaper than going to a movie!
Like others, I will also frequent the used book outlets for paperbacks and will take as many as ten if I have the room. At $1.50 t0 $3.00 these are a bargain for two evenings of entertainment.