We started by looking at the children's bike trailers of which there are a lot around including Croozers, Burleys and Pacific (the most common in my experience) just to name a few. So we thought the best way to test some out would be to hire them from a local company who provided a great home delivery and pick up service! The ride was fairly successful but the trailer system had a few disadvantages. Firstly as you can see from the photo below our two boys only just fit in it!
They were only 4 and 3 at the time so it was apparent that given there growth rate it was only going to get more crowded in there as time went on! Secondly I did not like the idea of the kids being so far behind me - I sometimes forgot they were there! More seriously though it was difficult to point out items of interest on the ride or referee the odd disagreement they would have whilst sitting out of direct view in such close quarters.
Whilst bigger trailers were available then the one we had test ridden, it was decided that even those would at best only last a year or so with our boys before we would have to look at other options. Thus the hunt was on for a bike that could fit all three of us!
But that is not to say that trailers would not be suitable for a wide range of people. If your children are not as big as mine you could get many years use out of a trailer. Indeed if I had my time over again I may have opted for one of the Croozer / Burley bike trailers that can convert into a stroller. When the kids were younger this would have been ideal as an alternative to a dedicated pram or stroller eg ride to shops, disconnect from bike, load in the shopping, hitch it back up and ride home! The newer models also fold up very well for putting in the back of the car when a car trip with the kids is unavoidable.