I'll second the recs for Patricia McKillip, Victoria Goddard, and Katharine Addison. Also, I'll rec Rachel Neumeier's Death's Lady trilogy and House of Shadows duology, and many other books, which, while starring young people, aren't young adult genre in particular. Have you read Tanith Lee? She was a master of the odd and dreamy and darker turns of fate. Her Kill the Dead is one of my favorite re-reads.