We've decided to finish it off the same way that the recent lanai work was done. Cedar on the walls and ceiling. Sheathing on the rafters. We haven't decided yet about the floor.
The work went quickly. David was a miracle worker when he integrated the weird angled connection between the two levels. The livingroom is a foot lower than the bedroom building. And there is a ramp between them. And just to make it more difficult, the buildings are offset and at angles. Somehow and David came up with a solution that looks natural and nice, without just building a false wall and thus robbing space from the hallway.
(Looking down at the odd corner connecting the two buildings.)
Nor did he cut out any of the structural wood which would have compromised the integrity. The work went quickly considering the odd angles involved.
Originally the space between the buildings was open. But we enclosed it. A solid wall made the new hallway too dark even with all the windows. So we added a window on the opposite wall.
(The door leads to the outside. There's a tiny little porch and a set of steps.)
This hallway is wide enough to be useful. Perhaps a writing desk? Perhaps bookshelves or storage of some sort? Right now it just is a space to store assorted "stuff".
Years ago when we enclosed this hallway we put in a pet door. It was a plastic one that is sold in pet stores. Over time, it had cracked. We didn't want to eliminate a pet door, so I had assumed that I would have to buy another one, but David said he could make one. What he made actually is better than the pet store kind. In the picture below, the slider is in place, shutting the pet door.
Here the slider is off, allowing to doorway to be used by the cats and dogs. There is a black rubber flap over the opening that swings when the animal use the door. The flap keeps out mosquitos and flies.