I use a heavy hard chain (similar to a New York chain) at the library in a nice area with nicer bikes than mine at the rack. But usually, I wheel the bike in EVERYWHERE and don't shop where I can't. I was folding the bike and carrying it into the library, legal, but a super pain in the neck. But I would do that in our downtown area. Now, I just don't bike to that library any more.

In the old days with a LWB recumbent, I used a big U-lock around the frame and rear wheel, with a relatively thin but long cable from the U-lock through the front wheel, as I couldn't fit that additional bulk in the U-lock anyway.