I adore Cyteen, once you get past the THREE unnecessary prologues. (No, I don't know why.) Telempath is, IIRC, about TWO completely unrelated apocalypses: a mutant virus causes everyone's sense of smell to become so acute that they go insane and kill each other (no, I don't know why) BUT LUCKILY it also enables them to evade the invading killer aliens who are gaseous and can only be detected by smell. Obviously I hope you read that one. ;)

I didn't really enjoy Enchantress From the Stars that much but it has a really fun central conceit: a girl from a high-tech world meets a boy from a low-tech world; her POV is written as sf, his as a fairytale.