On our tour this spring (two months, Italy-France-Spain) I was pretty happy with a button up shirt, which could cover my arms for warmth, be worn unbuttoned if it was too warm, and taken off without dealing with the helmet when it was really not needed. And when it was clean, I could wear it as "civilian" clothing.

I did have occasional thoughts that a bolero might be nice, but having multi-use items was more important to me.