And although i have not visited the zoo yet i would also like to bring up something completely different. What's about the penguin house at Loro Parque?
I was really impressed by the penguin house when I visited - wrote about it at length in my travel thread - not sure it's easy to compare with most of the other bird houses here though. How much one values species/biome diversity influences things massively I guess. It's definitely the best at what it does in Europe (that I know of at least) though. Interesting point.