Your older kid is rather older than the last time you asked about recommendations for children, but my own suggestions still stand:

Japan with baby (2.5 year old)

I’d like to reiterate the advice I gave in post 26 in that thread and that’s the importance of you adults having quickly removable shoes and your responsibility in gauging where shoe-off and shoe-on zones begin and end with regards to infant and children’s play areas. As parents you are going to be thrust into acquiring mastery level shoe shedding awareness compared to that expected from other tourists.

https://www.flyertalk.com/forum/31968482-post26.html