I prefer the LX lounges in ZRH, and especially the E gate SEN lounge from where the Yokyo flight will depart from. The outdoor terrace might be fun for the kids. In addition, with a family I would say ZRH will be a slightly calmer transit experience compared to FRA.

On the point of NRT vs HND, I have always preferred HND but some recent experiences with really long immigration lines at T3 at HND have meant that it’s practically faster to get to your end destination from NRT regardless of its distance from the city.