My eldest is 6. If we ride to the park and back from the park and do the boring bit of path near the nearest gate, its not really a great day out for anyone.
Cargo bike? Trailler? Trail-gator?
It's pretty mad that we accept pollution and rat-running to make life easier for parents. Especially as the main beneficiaries (by volume) aren't actually parents but instead perfectly fit and healthy non-parents who could cycle or walk but prefer to save five minutes.
Being a parent of young children is only 6-10 years of your life, whatabout the other 60 years when you could be enjoying a low traffic, low polution park?
(I'm the parent of a 3 year old, fwiw, so I know how annoying and exhausting moving children around is.)