I would like to suggest some simple quests linked into the different stronghold purchases to really encourage people to put the time into developing their stronghold.
What I am envisioning is something quite simple. Once your stronghold reaches a certain level of development, lets say for example inn, smith, alchemist you can purchase a quest master.
Quest master has a list of quests varying from simple to hard. Some examples would be to gather recipes for the alchemist to enable purchase of some extra buff potions or scrolls or ingredients to create such items, gather materials for smith to craft into medals and other gear.
Some quests would be chieftain only also. Chieftain only quests would be quite challenging but not ridiculously obscure and would provide such things as a rechargeable mass recall item with use of once per week only useable by the chieftain.
The theory behind this is to give people more to do once they have hit the end game, and items such as rechargeable mass recall offer options with exploring, escaping from ambushes, and gathering the balls to fight...
AND the same hints would be provided to everyone, in theory meaning that every clan would eventually have the capability of attaining the stuff