Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Longing
"The Piazza" has little in the way of plot or character; even its setting is vague and misty. Almost all there is to it is a tone of dreamy, elaborate longing. The narrator longs for a piazza, and then when he gets the piazza he uses it to sit and long to be off into the hills to fairyland. That longing is then mirrored back in Marianna, who longs to meet the inhabitant of the narrator's cabin. Marianna may or may not be a dream—the uncertainty about what is real and what isn't adds to the sense of wistful, uncertain desire that covers the story like a wet Kleenex.