Well, I have heard that Gokayama is less tourist-customized.
Still, I suppose Shirakawa-go has been good
both at welcoming visitors and at preventing overtourism.
When a long-existing natural or cultural site
becomes convenient to tourists,
some people may criticize
like that the original vista or atmosphere is getting lost;
however,
if no change or modification is made,
it may become harder as time goes by to appreciate the true value.
visiting Japan for 15 nights in early July just before the 2020 Olympics. We have 2 kids, aged 6 and 8. Is the seventh birthday of the smaller kid later than April the 1st in 2021?
In that case,
that kid, under certain conditions,
can travel in Japan free of railway and bus fees until March 2021.
Day 4 - DisneyLand Day 5 - DisneySea I recommend that you either choose one or set them on nonconsecutive days.
Exploring plural amusement parks on consecutive days
may not give little kids enough rest time.
In the middle of July,
for many schoolchildren the summer vacation may have already started;
Tokyo Disney parks may be crowded,
especially on Saturdays days, Sundays and holidays.
(In July 2020, the 23rd and the 24th will be the only public holidays.)
Guests of Tokyo Disney hotels and Tokyo Disney Resort Official hotels
who hold a valid Park ticket
are guaranteed admission to the Tokyo Disney park
even when the entry is restricted due to crowdedness.
Day 7 - Day Trip to Hakone Hakone Freepass sounds worth considering.
https://www.japan-guide.com/e/e2358_008.html