The structure generation of Cornucopia is ready, but still needs some tweaks like room types and interior generation. Maybe the smallest room size could be 5x5 rather than 4x4, because smaller rooms tend to squeeze themselves into strings of rooms which don't always look that great.
The green rectangles are yards. It's a feature that can come after a room (as the yard of the room) or as first feature. I think it's a rare, well, feature in roguelikes to have yards in the dungeon.
After those tests I added two different room types randomly to make it more colorful and it does work quite nicely, when you have more room types than just one. At the moment there are only three features: room, yard and corridor, but I think it already looks nice. The interior is more important than the "shape" of the feature anyways.
This routine is probably going to replace 'small room' routine used in various level themes and I like the idea of "layered" generation starting from basic dungeon and then adding stuff like this.
If there is one thing that bugs me it's that backyard in bottom right corner of the screenshot. It doesn't seem to have a door connection which could be some kind of rarely occurring bug. So maybe it would be wise to create important stuff like stairs only to the basic cave area.