Additionally, if you have any interest in Alzheimer's whatsoever go and find some of his writing and speeches. It's in my family and in part due to his words I'm starting to think more about it and my own way out.
If you're in the UK the BBC did some adaptation for BBC7, Mort was the only one I've listened to but it was really, really good. If you've got access to iPlayer it might still be there.
And I love Nation, I think it's one of his best. Not a Discworld book, but still very Discworld.