Ecco, I’m going down to the Garden Route in December with my family (I grew up in the area), so one cool thing you might want to consider is tickets on the steam train (I’ve never been but bought tickets in the hope it is as much fun as I remember when steam trains roamed the area):
https://scrail.co.za/
Don’t forget the Outeniqua Transport Museum in George if you’re interested in seeing some truly amazing trains in a warehouse environment:
https://share.google/HZ0hsnVytfo2FsLYt
If you crave a modern mall, catching a movie etc, the Garden Route Mall in George is good for that:
https://www.gardenroutemall.co.za/
Brenton-on-Sea just outside of Knysna is an amazing drive to a small town (complete with beach and restaurant). I remember the butterfly reserve outside the town.
Mossel Bay’s big cave overlooking the sea (complete with local dassie population) is a crowd favourite. And while you’re in Mossel Bay, a visit to walk on a ship and look at the local post office tree will drive the kids wild:
Bartolomeu Dias Museum Complex
https://share.google/6iMzy4Xw4dimA6Pca
If you discover anything else worthwhile while you’re down there, share it here! I’m subscribing for last-minute ideas.