My reading habits are all over the place at the moment - I'm not good at setting aside the time to read, especially for books that are too bulky to read on the train. But the final Discworld book is going to be pretty special - I suspect that when it comes to introducing the Discworld books to my son (Not counting "Where's my cow?"), I guess that the Tiffany Aching books are probably going to be where I start.
(Note - this is an affiliate link, meaning that if you use it to order this book from Amazon, then I get a small referrer bonus.)
(Edit - This is a lovely interview with Rhianna Pratchett, published shortly after Terry's death.)