I'm imaging myself around 20 and missing out of a couple of decades of great reading: the Aubrey/Maturin canon - Patrick O'Brian any book in the Discworld ser

I'm imaging myself around 20 and missing out of a couple of decades of great reading: the Aubrey/Maturin canon - Patrick O'Brian any book in the Discworld series - Terry Pratchett anything by Iain M. Banks (although, strangely, I don't find his non-SF as compelling; perhaps it is too dark for my tastes). and something to stimulate me to learn Lisp then instead of now.