Avi is definitely one of my favorite authors of all time. He has a way with a story, for sure. One problem I have though - is who to recommend his books to. Currently, his books are cataloged in both the Juvenile and Teen areas of my library.
The Seer of Shadows is one that is currently not shelved in the teen area. But I think the spooky setting and ghost character would appeal to an older audience.
I will be handing it off to some of my test readers to prove or disprove my theory shortly.