Hi Mike,
The Assembly always has a theme (builder or construction method), but Assembly is really about fellowship, learning and fun activities. That said, I really appreciate the thought behind your post, but let me suggest something a bit different that maintains the focus on a particular builder. I understand what you're saying, but on a large scale Old Town is probably the only builder that's nearly so readily recognized. All others (including modern builders) will likely have not nearly as great a following. And many of those lesser-known builders are absolutely fascinating... as long as you know of them. Morris, for example, built truly excellent canoes, and has been the subject of a lot of press in Wooden Canoe and other venues. So among wooden canoe folks, Morris is fairly well known but it will never attract as much attention among the larger masses.
Suggestion - an education campaign. Instead of simply saying "The featured canoe will be Kennebec" (next year) and showing a cool t-shirt design, promotional materials on the web, in the journal and elsewhere can have a short description of the exciting things about that builder's products and history, or great photos of their canoes in action. These teasers could vary over the year leading up to Assembly so that people get more enthused as time gets closer.
Just a thought, for what it's worth. - Jim