Yep, I've read most Pratchett books ten times or more in 3 different languages, apart from those I've only read at a library. He's been my favourite author for a few years now.
Have you played Classic in C#? Using command blocks to teleport and such, you could probably make an attempt at the library... But... well, not all of it, until they make a mod for walking upside-down on the ceiling xD
The problem with my answer is that i read also The Wit And Wisdom Of Discworld, which made it REALLY hard to answer that. i like The Reaper Man, Thud, Carpe Jugulum and Going Postal and several other books, more than the rest. it hard to pick a favorite, since they are ALL great books! I just want to know why doesnt the Duck Man know he has a duck on his head.
I just cant wait for Snuff!