Many depictions of traditional libraries prominently feature marble busts of writers, philosophers and various historic figures. I would like to stress the importance of such elements in home library design. Here is why.
One of the most basic principles of design that I try to follow is the need for balance between various shapes within the same space. To my personal taste, a room that consists largely of the same types of shapes or surfaces (for instance round tables, round stools, round place mats - and all that in an oval room to boot) cannot be seen as a well designed space. Now, libraries by their very nature make the prevalence of squares and rectangles unavoidable. Books are notoriously angular and bookcases are usually nothing but fractal rectangles of sorts (here is an example of rather unusual bookcases, however). This design handicap is well understood by all, so not much is needed to rectify the situation. One can employ crown moldings, wood carvings, furniture with rounded angles etc. Of course, some individual accents are an excellent choice. Marble busts work great for this purpose. Not only they provide visually appealing curves and various shapes. The very color of the stone stands out, because only occasionally book covers and spines are white! That's why I would recommend marble (plaster or alabaster are OK) busts as opposed to bronze. Not to mention the fact that busts and sculptures add a certain human dimension to any space.
The choice of marble busts these days is quite wide. You shouldn't have to hire an artist to make one unless you want to immortalize your own likeness. Here is a quick sampler of personalities that have inspired home library owners for generations, depending on their intellectual sympathies:
Philosophy: Plato, Aristotle, Pythagoras, Voltaire
Literature: Homer, Shakespeare,
Music: Beethoven, Mozart
History: Pericles, Lincoln, Herodotus