Venus Plus X

Badly dated lecture disguised as a novel about possible sexual evolution. Charlie Johns is caught by a time machine and brought to the world of the Ledom, hermaphroditic beings living in a world of bliss. They escort him around their world, showing him its various aspects, explaining that later they will "want his opinion." The better parts take place in or around the 1960 publication date of the novel, where Sturgeon has fun showing us the lives of husbands and wives who just might be headed in the direction of the Ledom.

I confess I haven't finished this yet. I probably will because I am so near the end, but things have really bogged down into a true lecture that goes on for many pages. I am sure a twist is coming, but I don't much care what it is.