This comes from a lifelong student of life sciences. I majored in biology but just continued on my own after the money ran out so I might be a little biased about what constitutes interest in a zoo but the best experience I have had with a zoo are the member appreciation days where you can talk to the people that make the zoo work and actually find out what the zoo does as compared to what they used to do. My home zoo is Omaha Zoo and their genetics department is top notch and field research projects are furthering the understanding as to how much life there is to appreciate and to conserve it and devise options to even maintain a population of people interacting with a non human population. That is what it is in my interest and what I find intriguing but I am noticeably a minority in the larger demographic of zoo patrons. There is a huge demographic of parents with children who just come to see the animals and that's it. I think this is changing with the awareness brought about by zoos, that the species that people see are in trouble; iconic species such as the African lion. Its hard to say what effect outreach programs have. I once attended a presentation on Madagascar, in the winter, and in single digit temperatures and I think there were probably fifty people there, many of which were students.
It has been mentioned, I think in a TED Talk, that due to the pace of modern society, that there are instances of many people that just do not allow the time to see such things as blossoming trees or see a beautiful sunset and so there is simply not the impulse to understand anything beyond their schedule and thus preserve or cherish it. However, many workplaces have matching fund programs for such organizations as the World Wildlife Fund, and this allows a consciousness raiser to be interjected into a busy schedule.
I think that in the course of a day, even small reminders of the "outside world" would benefit interest. I have seen many commercials lately that do just that with prime time slots for zoos. Zoos are convenient as a family venue as well. I have two within a maximum of two hours drive.
So that is where the questions of this topic have taken me. Its getting late but, off the top of my head, that is my addition to the topic.