Thanks for all the input. The day after my OP, I went for a ride. Temps were in the low 30's with decent wind. I was wearing a craft base layer, regular jersey and arm warmers. Decided then that a vest would be the route for me. Ordered it that night. I'll have it Tuesday. If I find I need a jacket when I start commuting in the cool darkness of the morning, I'll get a jacket.

http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

At $30, it's worth the experiment.