Can you stomach Varley? He did some interesting things with gender-as-a-conscious (and variable) choice in the Eight Worlds stories (before he decided he was the Nth coming of Heinlein); see "The Barbie Murders" (not exactly cutting-edge, but interesting) or _Steel Beach_. And MZBradley was doing some interesting things in the \very/ early Darkover books -- rather passe' now, but surprising when you realize "The Planet Savers" and "The World Wreckers" were published ~1960 (IIRC).

/CHip