@gillies never under estimate the awkwardness of manoeuvring heavily laden cargo bikes!
Hopefully you'll be using it all year around so you'll need to factor in getting kids in/out in rain & dark then getting them inside, then sorting the bike out. You'll soon get adept at dragging these bikes around. Ours has cable steering so has 150 degrees of movement which is massive compared to steering/track rod steering but is super useful when manoeuvring into tight spaces.
If you go away on weekends/holiday I'd be tempted to keep the bike in the house. Pain in the arse, but so is losing a bike!
I would also recommend running a dynohub so you can have permanent front/rear lights 24/7 for added visibility. You won't notice the drag.