http://www.chariotcarriers.com/Before I even get started I know this is a BIG investment for a couple with children, but IF you bike, jog, X/C ski and hike this is a good investment. All we had when the kids were little was a couple of back packs, a Fjellpulken (from Norway), see link below to move the kids around. This Chariot thing is fantastic. We helped the kids buy one and all the accessories except the hiking contraption as we all believe the X/C belt will suffice. Besides we all like to use trekking poles when hiking and the hiking accessory would just get in the way of the trekking poles.
If you and your wife enjoy the out of doors as much as we all do and do all kinds of activities then consider this. It is a well thought out product that does a lot of things well.
This last link if for you people that are die hard X/C people. We finally gave ours away to a family in Dryden, WA. It is 31 years old and still going along fine. But it only does one thing, and it does do that extremely well.
http://www2.fjellpulken.no/index.php?option=com_content&task=view&id=2&Itemid=36&lang=en