If your travels ever allow, give https://www.omahazoo.com/ a chance. It is consistently rated #1 in the US. Plan for at least 2 days to begin to see it all.
San Diego Zoo (giant Galapagos tortoises and Komodo dragons were the high point for me - can you imagine the veterinary expertise they have on hand there???)
The Sydney Aquarium (one of the only places to see a live dugong), and also in Sydney the Taronga Zoo.
The Rhododendron Garden in Portland, OR. An astonishing explosion of color each spring with the added attraction of a variety of water fowl that come to the lake.
The Japanese Garden in Portland, OR. Designed by a renowned Japanese gardening master. Located near the zoo and looks out over the city with Mt. Hood in the distance.
Peninsula Park Rose Garden, Portland, OR. A beautiful neighborhood park that is completely maintained by volunteers.
Pretty much all of the wildlife preserves in Africa, including Masai-Mara and the Serengeti.
Three that immediately come to mind are the Baltimore National Aquarium, the Oceanário de Lisboa and Sylvan Heights Bird Park, which is in little bitty Scotland Neck, NC. The latter is much smaller than the others, but it’s very attractive and well planned. It specializes in waterfowl, but they’ve been expanding their collection in recent years.
The Cleveland zoo isn’t bad, but especially the Rainforest building. It’s a great place to go in January or February to shake off the winter blues (but be sure to wear layers you can remove, because of course it’ll be hot and humid inside).
Zoos: Well, I love the San Francisco zoo, because it’s right here in town and I can go when I want to. And I have some nostalgic appreciation for the National Zoo in DC, and the French Creek Game Farm in West Virginia (a small place featuring wildlife that lived or had once lived in the Appalachias, where I went many times as a kid). But the best ones I’ve been to were the San Diego Zoo and the Mexico City Zoo. There were a wide variety of aimals there, kept in spacious enclosures and who seemed to be well taken care of.
Aquariums: I’ve only been to the one at the Exploratorium; I would love to see the big one in Monterey.
Parks: either Golden Gate Park in San Francisco or Balboa Park in San Diego
The Huntington which has museums, gardens, a stately manor, and two tea houses (one English style, and the other Chinese). The gardens are zoned, but I love them all. I was wearing a Huntington T-shirt the last time I saw my doctor. We had a nice talk about how we both loved it. He takes his family often.
The Los Angeles County Arboretum. It’s almost too big. Don’t got on a too-hot day! But it’s a fun place to walk around. Plus Lucky Baldwin’s cottage, aka Mr. Rourke’s house on Fantasy Island. Also, Lawrence Olivier’s Bolivian (?) house in Marathon Man.
It’s been over 20 years since I was there, but the Jacksonville Zoo was such a favorite with us when we lived in Florida that we had a membership for a number of years.
And, as mentioned already, there’s the aquarium in Baltimore, which we’re also members of, even tho we live in southern Maryland and go maybe once a year.
The Ragunan Zoo in Jakarta, Indonesia, is notable for me, as one of their giraffes took a liking to me, and unfurled his magnificent tongue around my forearm (presumably to lick off the salt, from my sweat). Giraffe heads are BIG and their toungues are LONG!
Aside from that remarkable experience it is a horror show - the long Orangutan in a sqalid cage, their lone Indian elephant chained on all four legs. Would never recommend that place.
Good zoos/aquariums: the Gerald Durell Zoo on the island of Jersey, UK and the Zoo dos Lagos in southern Portugal. The Oceanário de Lisboa in Lisbon, Portugal. The 2 Oceans Aquarium in Cape Town.
In the UK I’d say Longleat Safari Park. There’s a small zoo-like bit for the small animals but the majority is the park where you drive in amongst the animals. Once had a young lioness walk up to the car and looked in from about a foot away. Then there’s the stately home you can tour.
Kurihama Flower Word about an hour’s train tide south of Tokyo. Miles of trails cutting through fields of flowers. Just over a small ridge is a playground with a 40 ft. high replica of Godzilla. Kids can crawl through his crotch and slide down his tail!
I’m not a big fan of zoos but of those I’ve visited (Philadelphia, Washington DC, Baltimore and St. Louis) I would choose the Maryland Zoo in Baltimore. It’s nicely laid-out and I think the animals are given adequate living space and are treated humanely.
Longwood Gardens in Kennett Square PA is a nice day trip just about any time of year. Their decorations for Christmas are spectacular.
It’s been years since my last visit but the National Aquarium in Baltimore is impressive.
Philadelphia’s Fairmount Park is relaxing, scenic and pleasant.
It’s been a long time since I’ve been to these places, but I was very impressed with Butchart Gardens in Brentwood Bay, British Columbia and Hawaii Tropical Botanical Garden on The Big Island.
I love UC Botanical Garden on the UC Berkeley campus. It’s not a tourist attraction, but the place is beautiful and very interesting for anyone who likes botany.
I’ll add another vote for the Monterey Bay Aquarium. It really is a special place.
Point Lobos State Natural Preserve in Carmel-by-the-Sea, California, is a very beautiful place. Poet Francis McComas called it “the greatest meeting of land and water in the world.” A friend I once took there said about it, “Everything here looks like a Sierra Club calendar.”
Bryce Canyon National Park really impressed me when I visited it years ago.