My favorite is my latest game as a republic. Managed to do very well for myself regarding actually having a large number of sons to go run my trade posts. However, they were clearly bored waiting for me to die, so my second son started an adventure for the remnants of the Republic of Amalfi (which, mind you, wasn't all that much, since I already conquered Amalfi itself, and it was reduced to one city in Sardinia). My third son thought that was a great idea, and also decided to start his own adventure.
I decided they were being fools, and didn't answer their requests for help. So, despite having these hosts, they both managed to not win their respective wars. And the oldest even managed to get himself capture and castrated. By a republic with three trade posts and not even a full county to its name. Pretty sad.