There are some books that an established author can get published but which, coming from a novice, would never see the light of day. It’s not always a question of quality, either. A “concept” book may only be saleable with a big name attached. This is a case in point.
The concept behind Changing Planes is that, given the right set of physical stimuli, a person can travel to other “planes” of existence, populated by intelligent nonhuman races. The stimuli in question include tiredness, boredom, and slight nausea. In our society, they’re best found in airports, waiting for delayed airplanes. In theory, you can spend the two-hour layover in O’Hare as a week-long holiday on some alien planet.
The book itself is a description of some of the other “planes”. Each description is almost entirely plot-free, and some are pretty heavily polemical. But the ideas are different enough, and intriguing enough, that Le Guin manages to sustain the idea for the entire book. She would be well-advised not to do a sequel, though.