Japan

Kyoto for sure. Much more “approachable” than Tokyo.

I'd comment that Tokyo is very easy for English speakers, if you like a big-city experience. I don't mean that people speak English, but that the subway stops have numbers as well as Japanese names. Osaka is also easy to tour without knowing Japanese. Kyoto is a special case of smaller city, but I think the beauty of the temples, and the views and gardens of the bigger temples will interest children.

Check dates for Chrysanthemum festivals.

EDIT: Some Japan Rail offers may be available only for advance purchase while still in the USA. Local Japanese offices of Japan Rail were very helpful when we arrived with advance coupons.

We loved Japan, spending 6 days in Tokyo.
We did a day trip to Nikko north of the city. It is amazing, famous for the 400 year old cedar trees.

Kamakura is south of the city and we did a day trip there. The giant Buddha is amazing.

Kyoto is NOT to be missed. We did a three day tour from Tokyo that included a half day tour of Nara and two full days in Kyoto. The tour included RT on the high speed train. If you go to Kyoto, be sure to take a tour that includes the KEY shrines and temples. There so many that you can't see them all. Be sure to see the Golden Pavilion and Silver Pavilion. Also, the Philosopher's Walk that includes several shrines and temples.

After coming back to Tokyo, we took a cruise that ended in Hong Kong, that was great. We stopped in Kobe, and visited Osaka Castle that was great. Another great place to see was Himeji. Also, we visited Nagasaki and Okinawa.

Check out my trip report--I visited Japan in Mar 2023. If your kids like Sanrio Characters (Hello Kitty), then take a commuter train from Tokyo to enjoy Sanrio Puroland indoor theme park.

I am returning in Nov 2023 and Feb 2024!

Thanks all. This is amazing! I going to go through all your comments. We are planning to Fall 2024z

ORDtraveler,
Yes, we visited Sanjusangendo temple and it was amazing.

Everything ORDTraveler has said.

Kyoto for sure - beautiful, and what most people think of when they think of Japan. Hakone for varied and eclectic (and kid-friendly) stuff like sulphur vents, black eggs, cable car ride, pirate ship on the lake, hot springs. Might be fun to find a traditional ryoken there (hotel) for an "authentic" experience, sleeping on tatami mats, dining in kimono, etc.

I would also add the Ghibli Museum (Tokyo) if the kids are into anime and familiar with the Ghibli films - Spirited Away, Kiki's Delivery Service, My Neighbor Totoro, Howl's Moving Castle etc. https://www.ghibli-museum.jp/en/. It was not open yet when we were there in 2017 and my adult "kids" would have loved to go there. Big Miyazaki film fans.

I've been to Japan 5 times or so (I lived in Korea for several years) and absolutely hated Tokyo the first time I visited. It was so massive and overwhelming. Each time I've been back, I've liked it more. The trick for me has been to stay in a more local neighborhood and discover it a neighborhood at a time. With that being said, Kyoto is more accessible and has SO much to see. You could stay for a week and not scratch the surface.

Places I especially love are Nikko (if you like temples and outdoors, cute towns), Takayama (gorgeous historic central, wonderful outdoor museum nearby), and Hiroshima (local feel with visit to nearby Miyajima).

A couple of people have mentioned Tokyo being overwhelming and hard to approach. I find that a very curious and interesting narrative. Yes, Tokyo is large but you don't have to take it all in at once and there's no point in trying to try to do it all. Instead of being "greedy", just approach it a little at a time. Do some research on what is available to do and make up an itinerary.

I found the signage pretty navigable.

When I visited Japan, we had one week and we did visit Tokyo, Hiroshima, Miyajima, Kyoto etc. It was a lot and a lot of fun. You don't have to do all those places. One thing I definitely wanted to do was ride a bullet train which we go to do so travelling from Tokyo to, I think it was Hiroshima. If you and your family are interested in riding the bullet train, you might consider what attraction away from Tokyo would mean taking a bullet train. I thought it was quite enjoyable to ride the train and eat bento box for lunch. A lovely experience.

Our visit to Japan was in 1987, so some of the detaills are a little fuzzy in my mind. However, one thing that struck me was how child-friendly it was. Several of the sites, museums and castles, had costumes for children to dress in. There was a toy museum in one town. I’ll try to find the name and post it for you. Interesting for adults, too. There are towns that have craft centers where you can participate in a local specialty. We did paper-making, indigo dying, pottery glazing, and origami.

Not a popular opinion, but Nagoya is a great place to visit. I would recommend renting a car so that you can maximize your stay here. I believe Nagoya is underrated :D