In our library we do not quarentee quiet. We have hundreds sometimes thousands of people through the doors a day. We have two small group study rooms and one room we call the 'quiet room' (no talking allowed desks and tables set up for individual study or wifi/reading). Other than that people are asked to be considerate to others (we do often ask people to go to the lobby for loud conversations), we have large tables around the perimiters for tutoring and group work. Large multi computer tables for public use (we do limit cell phones at the computer tables but not in the main library) are constantly busy with people working, talking, moms with kids, kids sharing computers etc. Very busy, sometimes noisy but well used and someplace that people feel comfortable entering and asking questions.
Libraries have had to change with society. We are no longer a rigid institution. We are open and friendly and we want people to come in. People use to avoid libraries because they saw them as cold, rule driven, unwelcoming places with old ladies saying "shhhh" all the time. That's not who this society is anymore.
We seem to do okay with our large quiet reading room. I think people wish there was public use computers in there, but then again we constantly have people in here demanding unlimited time on the computers, unlimited use of meeting rooms for free, that children not be allowed in the library except for the childrens' area, oh and that anyone playing an online game or on social sights be made to give up thier time for people with 'important' buisness to do.
We're never going to make everyone happy, but I like the libraries today much better than 40 years ago.