I like some of those Alan Dean Foster covers. I've read a few of his books but not nearly enough. Kilishandra is nice as well. I always get a little bummed when i look for an ebook of an older title and it's not there. :(
What a great list of classic fantasy/SF books! I loved Killashandra, too - though I haven't re-read it recently, I bet it would make a great audio. Definitely more Patricia C. Wrede! And Shatterglass! I have read only half of the Chrestomanci books because I haven't been able to get them on audio from the library and have resorted to old-fashioned reading aloud to my son. Maybe Tam Lin by Pamela Dean or Mistress Masham's Repose by T.H. White for old favorites that are just not out on audio.
Oh, crud, I forgot Diana Wynne Jones! There are whole lot of her books that aren't available on audio (although I own a lot of the ones that are on Audible). I will have to start a new list.