I don't think I can do a good enough fort to be enjoyable by an Adventurer, but I'd certainly like to explore such a world.
You need to get more players into this! Kidnap puppies if required!
I can think of a couple suggestions...
* Build a fortress over a ruined fortress (I think it is possible, once found, the historic value would be really amusing)
* Using caves as "canvas"? Gives incentive to visit them.
* Forts over villages? A bit hard to do because of possible FPS issues but something like a castle with underground elements, and addons to the village so it's more interesting to explore.
* Non-fort but man(read:dorf)-made locations such as craters or detailed bridges.
* Allow simple cheating like [SPEED:0] so megaprojects, labyrinths and such can be constructed without much hassle.
In fact it would be possible to find a series of cheats and settings for Dorf Mode that can allow gathering story and site development faster.
* Explorer diaries! I know there is a lot of talented people around willing to write something like that. We only need to get them aboard!
As for Adventurer-oriented building, think of what you want to see. Watch an Indiana Jones movie (to mention one at random) and try to get the point into the structure. Don't make lots of empty space, put doors, traps..I don't know if caged creatures appear in Adventurer, but if they do, put them in. You basically need to forget what you learn about making an efficient fortress. Make it hard to get to point A to point B, or to obtain all treasure in a sitting. Put valuables very out of reach, make alternate pathways... You can do even one room for one given treasure, and do random stuff like floors literally full of coins (coin storage without containers? I think it is possible)
If you want to make big spaces, like a large balcony and such, use decorations, statues, armor stands...make it like you imagine medieval fanciness, with lots of stuff, engravings, rooms must have at least a minimal reason to exist, even if it's only say "this is a very fancy room". Chapels with fancy windows and with taller ceilings and stuff...And give nobility quarters they surely don't deserve. Something that tells the Adventurer "wow, the person living here had a room made of solid gold while everyone else was living in a shared room" or the opposite "this king lived in relative modesty!"
Another way to see it, is like if you were doing a Doom map. And yet another, think of levels in (old-ish tile-based)RPG titles or roguelikes, where every room tends to have a purpose of sorts.
http://www.bay12forums.com/smf/index.php?topic=60913.0 This app seems designed to work with such a project. It will help getting insight on the game entities.
Count me in on anything except fort making (I can do neat buildings and structures, but I can't make the fort live through to get good story). Find me on IRC for anything as well (DalGren@#bay12games).