Thank you Greyscale! Just took a minute to browse Uniqlo, and it looks like they might have the winner. 100% wool, and the price is very reasonable for an experimental item.
I still might have to go try on the J Crew knit blazers, because I really like the way they look, but my gut feeling (as Suz, Angie, and others have confirmed) is that they're not quite long enough. I like the look of the Madewell options, but the high synthetic content put me off. I've been trying to avoid synthetic sweaters, for pilling, static, and longevity reasons. If I had a Madewell near me where I could go pet them, I might change my mind.
Lisa p, I'll be curious to see how the static issue plays out -- I have a pretty good collection of thick wool cardis, all shorter/boxier though, and don't have much of a static issue with any of them. I do anticipate mostly wearing fitted rib-knit turtlenecks and henleys underneath, so bunching should not be a problem, I hope.
Part of my goal here is to push my cropped pants as far into fall as I can by upping the cozy factor of the outfit as a whole. I have a couple pairs of mid-calf/taller ankle boots on the way to try out as part of this experiment as well.