Most of Le Guin's work is about gender, one way or another! (Well, most of her later stuff, anyway - I'll confess to not have read a lot of her pre-LHoD Hain novels yet, shame on me.) She was one of the first major SF authors who really embraced the idea that you can do hard SF that's focused on social engineering rather than aerospace engineering, and if you're liking LHoD you should definitely go look for more of hers! (Even the Wizard of Earthsea books - the YA fantasy series - have a ton of chewy stuff about gender worked in.)