I agree this is a wonderful idea and it has encouraged some creativity among the staff. They change somewhat frequently depending on what they want, but one of the aquarists created a freshwater shrimp tank that has proved to be surprisingly popular with guests.
Omaha has indeed been a dominating force on this thread, although their lead will only last for approximately another 24 hours.

Just about the entire zoo has mentioned in some capacity, but if you've been following their progress in recent years that shouldn't be surprising. This was the zoos final entry, although by next year they may have an eighth on their hands if the revamped orangutan building turns out well.
I get why the indoor biomes wouldn't make it; they're really just inferior versions of the similar exhibits at Arnhem. However, in my opinion Sea Lion Shores would be a shoe-in. It's one of the finest pinniped enclosures in the western world in both husbandry and presentation. An argument can certainly be made for Asian Highlands as well, but I think Kingdoms of the Night, African Grasslands and Sea Lion Shores are all strong contenders for a worldwide must-see list.