What's your favorite Diana Wynne Jones book (leaving aside Howl's Moving Castle, the only one I've read)? Do I need to read her series in order or are they the kinds of series where each can be read as stand-alones?

ETA: Also, has anyone read any of the Weetzie Bat (Francesca Lia Block) books? I can't figure whether they look stupid or intriguing and I've never seen anyone talking about them.