In my state (Colorado) we have something called a sanctuary [1]. From humans being put high up into the air (via a 40 foot tall bridge that crosses the entire complex) which simulates a more natural way for us to observe the different animals they house (they specialize in carnivorous species), to larger and more natural feeling habitats for each different species (over 720 Acres devoted to over 450 rescued animals)
They spoke of Zoos and how bad they are most of the time, however the Denver Zoo they said were better then most other Zoos in our country when it came to building decent habitats. However in my opinion the sanctuary is an example of how every Zoo should alter its setup. I wouldn't even mind helping donate to my local zoo for this change and I highly believe the masses would contribute as well.