I currently have a 5yo and 7yo - I did school drop off with a Burley Kazoo (trailer bike) for the younger and the older on his own bike. Next year they should both be on their own bikes. I used a double trailer when they were younger.

Looking back, I wish I'd done a longtail cargo bike - Xtracycle, BikeFriday Hauladay, Yuba, etc. Probably one of the folding ones - BF Hauladay, Xtracycle Cargo Node, whatever other ones. I know that Cargo Node wasn't out when I would have been buying anyway. Not worth buying one now, but I think I'd still use it some. The full cargo bike (bakfiets, whatever - with the cargo pod in front) I don't think I'd use as much now, as much as it would have been a little better with the young kiddos.