Traditional vs. Modern
There's also a choice for what kind of environment you create within new designs. Traditional designs for libraries are still popular to some extent, and they are still what a lot of people think of when they think of what a library looks like. Books piled or opened everywhere, heads down to read under a desk lamp for solo work, wooden tables, echoing high ceilings...
In contrast to the traditional, most modern libraries are being designed for collaboration, for comfort, for a wide variety of uses. I venture to suggest that this kind of environment is designed more from a 'customer' perspective which is a terrible way to refer to library users, but summarises that sense of being for the benefit of each individual visitor, no matter what their intended use is.
However, both these designs can potentially intimidate people and put them off using the building - it depends entirely on their experiences prior to visiting our libraries.