My motto when biking is the same as my motto when I was in the Boy Scouts, “Be Prepared.” That is why I own so many things ways to carry stuff on my bike. This motto has never been so true as when you involve children in your daily commute. With helmets, rain gear, and whatever kind of bike(s) you decide to go with you always need to think of what could happen, and have a backup plan in case things go horribly wrong.
To help you out a little here’s an interesting article from UtilityCycling.com about starting to bike with your family.
Albany Bicycle Coalition 