First time I'm posting and I'm not sure if said before, but I would like to offer a couple little ideas.

1. One idea could be a healing place or nursery. On this building, whenever a settler gets sick or has low health, they can seek treatment at this facility. You may slow down the healing process, and this facility will allow them to heal faster. You can also craft medication by gathering different herbs and berries that can be used for the general population and trading.

2. Maybe having the option to attack raiders instead of only defence. The attacks could be for settlements already existing within the map controlled by AI, or sending raiding parties to the edge of the map. Then, a statistics and options menu will determine the success of the raiding. Plus, if the raiding is successful, the remaining raiders will bring with them the spoils of war, as well as increasing prestige.