The best term to use to describe people who use the library is currently a somewhat debated issue. Patron is traditional but can be too closely tied to the old view of the library as only a supplier of intellectually worthwhile books to those people who come to the library. While the library still fulfills this role, it is beginning to branch out into countless other media, and a greater emphasis is placed on reaching out to draw the community into the library rather than waiting passively for them to stop by.
In this newer customer service view of libraries, customer is the more common term. However, to me at least, customer implies someone who explicitly pays for services rendered. Of course it must be remembered that people do pay for a library's services through taxes or other fees. Yet the library has a glorious tradition of providing information to anyone who seeks it, not only to those who currently have money in their hands.
Therefore I have taken something of a middle path and have used the term user for anyone who uses the library. This is a very common term in current information technology literature, yet at times it can be rather a cold, faceless description. It seems no word is perfect.
I have not differentiated in this report between the different staff levels; student interns and professional librarians are all described as simply librarians. Good customer service can be provided regardless of education level, and indeed, the interns often performed better than librarians on this issue.