score:5
How long I need at the peace dome?
It's just the ruin of a relatively small building to look at from the outside. The whole park, including the Sadako Sasaki memorial, takes an hour, tops. There's a museum that probably takes more time, but probably not a good place to take toddlers to.
Is Miyajima a whole day trip
With toddlers, it's at least a half day trip.
and is it worth seeing in early November?
Very much so! In fact, that would be one of the best times to visit, as the trees in maple valley should be in full fall splendor. And the kids will love the tame deer and the monekys.
What other things are interesting in Hiroshima
There's a castle (a reconstruction, of course) with a museum inside and a viewing platform on top.
How long public transportation takes
From the city center to Miyajima it's about 45 minutes (including the ferry ride), otherwise everything is in walking distance.
Upvote:2
I wouldn't recommend talking a toddler to any of the museums inside the peace park. My group (which were all mid-20s males) were pretty shaken by some of the stuff, and there were things that I wouldn't want to show a child just yet (the effects of radiation on people, there's a display that has mannequins of what people looked like post detonation), and maybe a few things that can shake you too. If you do go to the peace park (I still highly recommend, it is beautiful!) try to go on a sunny day, as I went on a cloudy rainy day and it just made everything even more melancholy.
If there are teams still playing, you can go to a few stadiums (We stayed near the zoom zoom stadium, but couldn't go since we were only there for a day) and maybe catch a game.