That is a very nice list Blackrhino, and don't feel bad about not visiting other zoos with top exhibits, i really believe you have seen some of the best that is there to see, with the exclusion of (Bronx, Omaha, and special exhibits in Detroit and Woodland park) hopefully the National Zoo as well
My list of top 10 exhibits in the US, based only in zoos i have visited:
1 Congo (Bronx Zoo)
2 Monkey trails and forest tales (San Diego Zoo)
3 Tiger river (San Diego Zoo)
4 Kilimanjaro Safaris (DAK)
5 Pangani Forest Exploration Trail (DAK)
6 Maharajah Jungle Trek (DAK)
7 World of Birds (Bronx Zoo)
8 Madagascar (Bronx Zoo)
9 Edge of Africa (Busch Gardens Tampa Bay)
10 Myombe Reserve (Busch Gardens Tampa Bay)
11 The Oasis Exhibits (DAK)
If the two Big Animal Theme parks in Florida were not considered zoos by most in the forum, then my list would look a lot different, but being a devote student of Zoo structural and landscape design, i can only praise this exhibits for going above what the average zoo design ends up with, thank you.
This list is of the US"s top zoo exhibits, not the rest of the World, having seen some of Europes finest, i will have to say that most of the top exihbits are here in North America, with its exceptions(Masoala Rainforest), in December we will be visiting Singapore, and i will have to see if the jewel of Asia has anything to include in this list.
European Zoo exhibits that i have visited and rank high, but not high enough to take down America's Giants are:
12 Hippopotamus House Dome (Berlin Zoo)
13 Asian Cat Jungle Building (Frankfurt Zoo)
It is funny how my favorite zoo in the World does not have any of the top exhibits in the World.
Top 10 zoos i have visited
1. Zoologischen Garten Berlin
2. San Diego Zoo
3. Bronx Zoo
4. Disney's Animal Kingdom
5. Antwerp Zoo
6. Frankfurt Zoo
7. Busch Gardens Tampa
8. Berlin Tierpark
9. Miami Metrozoo
10. Hannover Zoo
Other very strong contenders that i have visited based on a combination, of collection size, exhibits quality, zoo history, Architectural value, landscape.
Zoos that i will be visiting soon or are very high in my list of priorities:
Smithsonian National Zoo, Singapore Zoological Gardens, and Omaha zoo.