Oh, I'm full of ideas. For others...
Sounds great. I'm not asking for loads of children, but a few would liven up the place.
I've recently started a new game and haven't got far enough to try your Staff Agency mod yet, I haven't even got a place to stay unless you count Crosades' lice-ridden and moonsugar-stained skooma-infused bed.
I thought that might be the case, and fully understadable.
And I should have though of that before I posted.
My desire for a promotion system is that I think it could make the task of managing the estate more realistic. Say your guard captain dies, do you hire a new one or promote one of the normal guards? If you decide to promote a guard, who do you choose? You've already said the staff will gossip about each other, this could be a good way of putting that gossip to good use when you decide which guard becomes your next captain. I'm not sure why a specific guard would be better than another though, so this may well be overkill. I see the Staff Agency doesn't have Guards and with only one person for each position this idea doesn't make much sense. Perhaps something to implement if you decide on adding multiple people in a later version, so ignore for now
All good ideas. I remember reading about another mod (Building up Uvirith's Grave?), where people actually seek you out and ask if they can build a temple or tavern or what have you. I obviously don't know what the exact scope of Pegasus Estate is, but a largeish estate could have a small shrine and Guest house/Inn.
Ambitious indeed! And I think your plan on releasing it in bits and pieces as it were is a good one.