Bike Friday Haul-a-day
I'm 6'4" and my wife is 5'6" and we have had a Bike Friday Haul-a-day for a couple of years. We really like it and have used it quite a bit for riding with our two boys (even on a couple of multi-day tours). To convert between my wife and I, I just extend the frame and raise the seat, which takes 2 minutes or less. With the 20" wheels the weight is low and pretty stable, plus carrying kids or other loads on a cargo bike so much easier then hauling them in a trailer (in our experience). Highly recommended.