[mrwh]

Small Gods will always be my favourite (not least because I got mine signed by the man himself, many years ago in Dorchester. Though isn't the joke that he signed so many books that it's the unsigned ones that are more valuable?). For starters though, I'd pitch Wyrd Sisters or Guards! Guards! Both are wonderfully constructed, early, but late enough that he's stopped satirising fantasy novels and has started satirising the world.