Beyond the structure and simple reading experience, "Sea of Tranquility" seems to be Emily St. John Mandel's attempt to interrogate her own writing career. One of her main characters, Olive Llewellyn, is her doppelgänger, filling the same role Garp did for John Irving in "The World According to Garp." Perhaps some of my pleasure from reading this book came from how Mandel was able to draw in her previous novels, especially "Station Eleven" and "The Glass Hotel," and capitalize on all the good will stored up by them.
I don't know how "Sea of Tranquility" ranks in Emily St. John Mandel's bibliography: I thoroughly enjoyed every moment of reading it. I won't even invoke the "I was disappointed when it ended" trope because part of its triumph is its precisely crafted conclusion.