So, after playing Pillars of Eternity and the first expansion to completion, I've come to realize that the stronghold system, well, falls short. Drastically. And the reason isn't what most of you would think. Yes, I'd love a massive 3d highres sandbox that I could turn into a Gothic dungeon or mage's tower or Arabian palace or whatever, or at least the ability to customize my stronghold so that it isn't exactly the same as every other maxed out stronghold, but that's not the real problem.
The real problem is that it's useless. I played through the entire game twice now and only go back to the stronghold for attacks or to take advantage of the rest options. Oh, and the bounties. That's it. The shops are insignificant, the adventure rewards aren't anything significant, and the main keep doesn't really house anything. More to the point, though, it doesn't feature in the story at all, except for occasional mentions that you've taken it over. Now, Pillars of Eternity is hardly the only game to do this. Notably, Baldur's Gate II did similarly, though there I seem to recall there were at least a few unique events that required your personal attention, and a few unique items you could get for doing well.
I'd love to see a game much like Pillars of Eternity, except that the plot is somehow centrally tied to the stronghold. There's a world to explore, cities and towns to visit, side quests to do, and maybe even significant parts of the main quest out there, but the main quest brings you back to the stronghold again and again, and not for a gimmick, but for good reason. On top of that, at least some of the best equipment in the game can be gotten only through the stronghold blacksmith. The best potions can be brewed by the stronghold alchemist. The most devastating traps can be constructed in the stronghold tinker. The stronghold isn't just a minor add-on, an 'oh, and also'. It's part and parcel to the game on both a plot and mechanics level.
And yes, at that point you probably do want to give the player a slightly more developed stronghold system, but honestly, I don't think it needs too much more to be serviceable. I just, first and foremost, need a reason to care about it.
As an idea of how this could work, and yes this is heavily reminiscent of PoE; it's been in my mind a lot lately: The kingdom is suffering from something (the Legacy serves well enough). This something isn't easily explained as natural events or obviously tied to magical experiments. People are desperate. People are suffering. Throughout the kingdom there are various ancient ruins of a long-lost civilization which have never been thoroughly explored because reasons (unfriendly natives, superstition, dangerous monsters/traps, or just not much obvious financial reward). Now, though, because of the something, the king is looking for anything that can fix it, or at least shed some light on it. He's trying a bunch of things at once: the priests are making record offerings to all of the gods, even the minor ones, the mages are studying it all out with almost no restrictions, whatever level of 'science' there may be is given lots of resources, and the king has decided to commission adventurer groups to dare these ruins, in hopes that something in them may shed some light. I.e., most people don't really think you'll achieve anything. Even the king isn't putting much hope in you. But people are desperate. You, as leader of your adventurer group, are given a sizable plot of land that's never been developed because of the ancient ruins on it (maybe you have to compete for them as the intro/tutorial). You're given a sizable sum of money to develop the land with, to build housing, facilities, a library, magical research laboratories, a forge, a public bath, statues to yourself or others, whatever. You're tasked to explore the ruins and bring up anything that may shed any light at all on the situation. Of course, archaeology, translation, magical decryption, and physical repair of ancient artifacts aren't exactly adventurer bread and butter. So, you have to go out into the world and find the foremost experts, or at least whoever's willing to work for you, to do that for you. They need facilities to work in. The better the person is, the better the facility they demand. And the better the housing, and food, and local tavern, and local court, and.... Yeah, you need to spruce the place up to get started.
But, as you delve into the ruins and bring back artifacts, these experts figure out what they are, how they work, and what happened to the culture that made them. This is the primary story. So you don't get it directly from exploring the ruins, you get it from bringing the pieces back to your stronghold to be examined by your experts that you hired by having a nice enough stronghold and keeping them happy and being friends with them and maybe getting revenge on their ex-spouse for them and... Ok, so obvious side-quest potential there. In the end, at the bottom of your ruins, you find something. Something that's entirely out of place and makes no sense but there it is. My original idea was a spaceship. Perfectly fitted right into the solid bedrock. With no path in or out even a fraction big enough for it. So it's a little corny, but it'd work. Or maybe it's the Great Library of the Ancients. Or the Council of the Gods, the Well of Souls, whatever. Somehow, someway, what you find at least sheds light on what the problem is and what the solution is, maybe it even presents the solution itself.
In the end, you can have a vibrant living world with a driving reason to explore it (to find and convince experts to help you), but also a stronghold that's deeply integral to the plot, with some of the best facilities around (by the end, at least, thanks to all the experts you're bringing in). You go there to stock up, you go there to upgrade your gear, you go there to advance the plot (and with good reason), and maybe you even go there to get to know your people (the experts in this case instead of party members).