These look really good (I've actually read "Castle" and loved it, and have heard of some of the rest--but the unknowns to me seem even more fascinating).

May I recommend two American women mystery / thriller writers who have yet to receive the acclaim that they deserve: Margaret Millar and Dorothy B. Hughes (a bit subtler — and in my opinion more subversive — than Patricia Highsmith). Pick anything by either of these two and you won't be disappointed.