I feel the same way about the Oakland Zoo. It's a really nice zoo and I highly recommend it. I've been there dozens of times, first as a child, then as a teacher, then as a parent. I had a birthday party there as a kid; Trevor had a party there, too. I vividly remember a childhood field trip to the Oakland Zoo; I took my first class of students there as well. My parents had an Oakland Zoo membership for decades. Definitely visit if you are local or in the Bay Area for several weeks. But if you only have a few days in town, I think there are some places that should get a higher priority.
There's a special place in my heart for the Sacramento Zoo as well. My first visit wasn't until I was in college, but I liked it right away. It's much smaller than Oakland or San Francisco, but it is charming and worth a visit if you're local. We spent Halloween there in 2012, trying out their Boo at the Zoo event and it was fantastic.
San Francisco, Oakland, and Sacramento's zoos have something very important in common: the animals' health, safety, and comfort come first. This is a deal-breaker for me. Case in point: We have an animal theme park about 10 miles from our house, which started as a zoo showcasing African animals, ocean animals, birds, and more. When I was a kid, it was all about the animals and a nice place to visit. By the time I was teaching in that very city, they had started adding roller coasters. The animals were traumatized and many of the shows and exhibits were changed or canceled outright. Yet the roller coaster building continued and the animals have paid the price. I refuse to go there. I refuse to go to any place that doesn't put the health, safety, and comfort of the animals above all else.
That said, I do think zoos do important work and I am happy to support those which have their priorities in the right place. Here are the zoos that I think you shouldn't miss when you travel.
The San Diego Zoo is widely considered one of the best, if not THE best, zoos in the world. Add in the Safari Park, and you can easily spend two full days enjoying everything there is to offer. The San Diego Zoo is a destination in and of itself. Go.
I'd never heard of the Henry Doorly Zoo until shortly before we traveled to Nebraska. Never in a million years would I have guessed that Omaha is home to a zoo that rivals San Diego's for the title of best in the world! It was absolutely amazing, with so much to see and do. And what a bargain! Tickets are a fraction of the cost of the San Diego Zoo, but the quality is just as high. Possibly higher. I cannot say enough good things about the Henry Doorly Zoo. I'd return there in second.
We spent a blisteringly hot evening at the St. Louis Zoo and had a fantastic time. The lush, well-shaded zoo is home to what might be my all-time favorite zoo exhibit: Sea Lion Sound. I love that the St. Louis Zoo's motto is Animals Always. That philosophy is clear throughout every corner of the park. The zoo is in historic Forest Park and entrance to the zoo is free. I would LOVE to go back, particularly on a cooler day with more time to stroll and enjoy!
Trevor and I spent my 46th birthday at the Oregon Zoo and it was one of the highlights of our time in Portland. The only way to have improved my visit was if Steve had been able to join us and experience the zoo as well. I love how well the Oregon Zoo pays tribute to its location. And the art! My eye was constantly pulled between the animals and all of the art inspired by the animals. My favorites were the mountain goats. If you love goats, check out the Oregon Zoo's Tiny Goat Visits. I am obsessed.
I debated adding the National Zoo in Washington DC to my list, but I haven't been there in 25 years and my memory of it isn't as strong as I'd like. I don't know that it should be a priority over other Smithsonian museums if you have limited time in DC, but it is definitely worth a visit if you'll be in the area for awhile. Bonus - like most tourist attractions in DC, it's free.
I've heard really good things about the Bronx Zoo, but I have never been. I'd like to go someday, but I have a feeling that it is like the SF Zoo in a lot of ways - fabulous, but competing with so many other great tourist attractions that it is hard to justify adding it to the schedule if time is short.
If there are other must-visit zoos in the US, please let me know in the comments!