We don't have a lot of free wall space, not without sacrificing bookcases. But I had a thought. Given that the walls are so high, maybe we could do what we do in the classroom, and stack two boards, one on top of the other, on sliders. If we did that, I think we could actually do it in front of a bookcase, mounting the sliders on the edge of the bookcase walls. Is that crazy? We have a 6' wide built-in bookcase in the library in David's latest library plan (next to the window seat). Can we put sliders to either side of it, and mount two 4x6 pieces of slate on there? Ideally in such a way that we can slide them both up to the ceiling easily when not in use? We can slide them down if we need to access the books behind them, and if Kevin's actually using them, he could slide first one, then the other, down to easy work height.
Am I making sense? I'm picturing the library with a sort of industrial / steampunk vibe, with the Edison chandelier hanging above a round work table in the center of the room, a couple of comfortable leather chairs, a dark red Oriental rug, lots of books, and the slate blackboards. I think it could be really cool-looking and a great work space -- and when we're not using it for work, the kids can always draw on the blackboards too.