A light rail will keep intruders out of a private corner, and yet will not shut out light, or prevent circulation of air, or take away from the feeling of openness and breadth the library room ought to have.
For interior finish use few horizontal moldings; they make traps for dust.

Use such shades at the windows as will permit adjustment for letting in light at top or bottom, or both.

The less ornamentation in the furniture the better.

A simple pine or white-wood table is more dignified and easier kept clean than a cheaply carved one of oak.

But get solid, honestly-made, simple furniture of oak or similar wood, if funds permit.