Kean, for me, on a general level, the show really speaks to what we take for granted in our everyday life. It seems to be a celebration of the mundane, about raising pedestrian activity to greater significance, and about the passing of time. For me, the beauty of the play comes forth in Wilder's oscillation between death and life, sentimentality and cynicism. I feel like the end of the play is not unlike the end of Company, because the audience is put in a place where they (hopefully) see how fast it all goes, and how you need to be a part of it even though it's hard, and scary, and messy.
I have less than no background in drama studies, but I can guess that as a dramatic exercise, the Stage Manager needs to balance a sense of aloofness and objectivity with an underlying affection for the town and all its characters. I think the key is not to be overtly sappy and hokey - which frankly, is hard, given the text.
The morning star always gets wonderful bright the minute before it has to go --doesn't it?