For the life of me, I can't remember if it was called 'Fantastic Tales' or something like that, but the book I lost a few years ago had some very excellent short stories in it.
In one story, two geologists discover an opening to a subterranean world when they come across a ventillation shaft that leads to a giant air processing facility that provides air for a race of creatures who are similar to humans only they do everything crazy and backwards. The opulent women used products and treatments that make them look hideous, because they think it is beautiful and the lower-class women were gorgeous because they couldn't afford the treatments. They drive these little vehicles wildly about wherever they please, often crashing and dying. They wage wars with fantastic machines that shake the Earth above (origin of most of our earthquakes) and they have a theater where people can watch the wars in VR. The main charachter is captured and they try to execute him with a death ray but it doesnt work on his physiology so instead he is adopted into their society and actually thrives. He gets a job running the air handler facility and eventually discovers that one forgotten valve can shut air off for the entire subterranian world. Using this valve, he creates a tragedy which he 'saves the world' from and becomes the leader of the underground people. He eventually tires of the madness of the underground people and shuts the air valve off and leaves, returning to the surface with his friend. His friend had a similar experience that wasnt elaborated upon, as they were separated by a cave-in at the beginning of the story. His friend went on to become the leader of the rival clan to his own people and after they discovered each other they sent coded messages to one another and met up and played their people against each other to bring peace which ended up driving everyone crazy because they loved war so much.
Another story had astronauts exploring other worlds. They find a paradise where wonderful beautiful women sprout from plants that read their genetic makeup and produce their perfect mate. The head astronaut abandons his colleague who is enraptured and under the spell of the paradise plantwomen. He launches missles from space that obliterate the planet, since it would cause the downfall of mankind if they came there. They would be willingly enslaved by the plant women. He makes a log entry in his computer about how its like the 10th or 12th planet with such a type of alluring paradise that he's had to destroy in similar fashion.
Another brilliant story describes scientists who discover how to control out of body experiences and figure out how to project their minds to this other plane of existence. The problem is that whenever they do, they feel an invisible presence there that scares them so badly they terminate the session. Finally, one of the scientists gets brave enough to confront the presence, and unintentionally melds with it, discovering that it is the conscious mind of aliens far away across the universe who are conducting the same experiments with astral projection. They talk for a while and part ways, with promises to meet again and again, to learn and share with each other.
Please, if anyone recalls this book or any of the stories within, let me know what the title is. I would be most appreciative because I want to share these stories with friends. Thank you for reading and I hope someone knows the answer.