I have pretty vivid memories of the Last Battle too, but really, I have vivid memories of ALL of the books. The series was just...incredibly visual to me, in a way that I don't think I often see books.

Yes, Aravis is AWESOME! I liked her a lot at the time, though I wouldn't have called her my favourite or anything, but these days I just plain ADORE her. Today I'm pretty sure I'd like Horse and His Boy more for Aravis than for the horses, blasphemy though my younger self would have thought that!