I've abandoned pretty much everything I'm working on right now in favour of my sage green shawl. I love it. It's a less common construction, made by casting on the two bottom edges of the triangle and decreasing on every right-side row until there's nothing left. As I suspected, this construction goes very quickly. With a top-down triangle, the longest rows occur at the point where one is tiring of the project. Done this way, the longest rows are done while it's still a new and exciting project, so by the time it's getting boring most of the knitting is done anyway!
Some clever person on Ravelry worked out the completion percentages for each row of the shawl - I've only finished the first chart and the first row of chart two, and I'm 26% finished with the shawl. Hopefully I'll get a good-sized chunk of it done over the weekend, since it looks like it's going to be wet and gross again.