Good to see you again, FO Ron. How I envy you (in a way). You've got three more Tiffany books to read for the first time. And I also think that Tiffany may be the most fully developed single character Pratchett has developed.
I do think, however, that like all other Pratchett novels, these--especially the last 2, require at least 2 or 3 readings. Have fun.