Having done a few family flights in CS albeit mine were a good bit older here are my thoughts: I think it's preferable to all be on the same aisle being served by the same crew member. Also I think it's easier to physically attend to a child who is sitting directly across the aisle rather than in a neighbouring middle seat. However the seats in the rear mini cabin are staggered making it near impossible to see across whereas the seats in the main cabin are pretty much perfectly aligned.