I was thinking you could add a butchers so that you can control the slaughter of pigs?
Also perhaps allowing towers to be upgraded to allow for more citizens to occupy them(allowing for more and faster arrows for defense.
Make paths need stone so that there is a reason to find a mountain biome?
Allow warbands to use wagons for faster transport?
I also think a simple change should be that the new migrants message should say what settlement they are joining.