Okay, so having introduced this theme to every other thread, I have taken up the challenge of starting a new thread on the off-chance that someone other than me is interested.
We currently use a child seat and were somewhat restricted in finding one that would fit both a large men's frame and small woman's frame. My main complaint is that you can't carry panniers as well - and I can't ride with a backpack while child is in seat. So getting stuff (lunch, papers) to work is a challenge. Unfortunately, small person is also threatening to grow out of it.
We've been offered a used trailer and will probably try that in the New Year so we can take a friend home as well. But I'm not that keen on (eg) taking a trailer across Holy Corner (Merchiston Ave to Chamberlain Rd). I'd really like a Kangaroo bike, but the cost seems prohibitive, and I worry that the small wheels/gears would make getting up hills a challenge (good blog post here on a kangaroo in Scotland).
And then, of course, there is the trailer-bike (invented by a Canadian!). This seems fine for pootling about on the weekend, but I am less than convinced that my 3 year old would be happy holding on during our usual cold wet night-time ride home. Advice/experiences much appreciated.