What features are useful on a bike for carrying children? See also this question: What should I look for in a &quot;trailer bike&quot;/&quot;tag-along&quot; bike for a child?

I want to buy a bicycle.  I will want to use a child seat for a few years, and then move to a trailer.  I will be using the bike in a small UK town in light, orderly, traffic, to travel a few miles (At most 5 miles per journey.) on mostly level ground.  

What features should I look for when buying the bike?  What features would be useful?

What features are less useful?
In the Netherlands something has evolved that is (unofficially) called the "mammafiets" or "mothersbike" main features that make it a useful bike for cycling with children are:


A larger distance between the saddle and the handlebars to allow plenty of room for a child seat on the handlebars.
Wider handlebars to make it easier to reach around the kid in the front-seat, and to make steering with a kid in the seat easier (more leverage) and the ride more stable.
A support stand that has feet on either side of the frame to make it more stable when parking
A steer-lock to keep the front wheel straight and stable when your kid is in the front child-seat when you park the bike (very easy when loading a second kid on the back-seat or when opening shed-doors, etc.)
A lower saddle to allow you to reach the ground more easily with your feet
A slightly longer rear luggage rack to give the kid in the rear-seat a bit more room, and still allow for panniers.
An extra low step-through frame.


This is a typical example: