You can also try custom builders, if your need is such that it makes sense. We went custom because we are on our bikes a fair amount, all four seasons, and have taken the trail a bike as far as it can go. I would not recommend the Adam's version of same, by the way, to anyone that is using them day in, day out -- IMO they are not sturdy enough in the hitch for this use. The Burley Piccolo is surely a better bet in this regard.
We'll have tandem + trail a bike happening when number 2 son hits kindergarten. My 6 year old and I are proving this winter that we can get rid of one car by riding all winter long -- and we are hoping that Vancouver isn't going to have unusual amounts of snow!
We went custom because it allowed us to get the bike we wanted, with exactly what we wanted on it, in a geometry that allowed our rapidly growing 6 year old to do without the kid-back adaptor but without producing unnatural compromises for my wife either (either as stoker or captain).
Our new frame by Dennis Bushnell is supposed to be off to the painters soon, so I guess we'll be checking out our 6 year old against it fairly soon.
-- not an official company site but lists his email address.