Sitting in the library can be a good place to people watch. For instance, there's an older woman at a table working on some sort of craft project. A gentleman in one of the rows of books is talking on a cell phone in a language other than English (take it outside buddy). At a table facing the pond is an older guy staring at a laptop with earbuds in. I wonder if he's watching a movie?
In college, I went to the library to do homework once in awhile. My usual limit was about two hours before I got so distracted I needed a change of scenery. But to get something productive done, I basically had to kick myself out of my dorm room or apartment.
Anyway, the next time you are in the mood for some people watching (and the Minnesota State Fair isn't an option at the time), just head to your local library. You probably won't be disappointed.