I was struck as I read your comments to each other that as you used adjectives such as "stunning," "orderly," "valuable," you were describing different perspectives from which an object can be viewed. I teach (or have taught) every grade level and I think it helps to guide students toward thinking in terms of "perspectives" thereby allowing comfort for those who struggle with the absence of clear definitions.
I am interested in the strategy described "What is Beauty?" and intend to try it soon. One roadblock is that students' expectations of an art class rarely include examining ideas and beliefs. I know this is not a unique observation, but it continues to be my biggest challenge.