Our library is interested in a "scraf in a day" workshop. If anybody else has done this, did you dress the looms in advance? I know that a lot of people don't "get" warping right away and can take the whole day if they get it at all. I always prepare the looms for the kids, since I don't have the time to teach them that process, either.
I teach direct warping for the first hour and make narrow, long scarves. Most are 6" wide and 66" long when finished. I have my students warp onto the rigid heddle loom for a piece 6.6 inches wide.
You might consider a "quick" weave a long (WAL) to see what people come up with.