There's a reason people rave about the San Diego Zoo. I've been to a fair number of zoos over my life and, honestly, I most always go to zoos with some trepidation. While I know relatively nothing about how animals should be kept in captivity, let's just say I'm somewhat skeptical about housing wild, sometimes endangered, species for our viewing benefit.
San Diego Zoo is the best zoo I've visited. It's well worth taking a day to walk around and view their collection of wild life.