Jeremy
I am guessing you are meaning two different options for the one house? I don't think there is a way of doing that at the moment, but it is a very valid idea. Maybe a "SEO on/off" button in the Layer dialogue?
A solution you might consider for now would be to copy the Option A exterior walls to an Option B (with different intersection priorities of course) and SEO them with the Option B roof. Not too much drama if its only the exterior walls you need to do this with.