Anyway, just finished Lloyd Alexander's The Black Cauldron. I enjoyed it far more thoroughly than I did The Book of Three. There was a lot more depth to it. I particularly liked the dimension Adaon and his brooch added and the underlying theme of sacrifice. Good stuff!
If someone is willing to lend me The Castle of Llyr, I think I might add it to my 20-books-before-I-leave list. I'm eager now to follow more of Taran's adventures. And, on that note, if anyone wants my copies of The Book of Three or The Black Cauldron, let me know.