Later in life favourite authors

The recent death of Tom Robbins got me thinking...there are so many authors who influenced me in my 20s...Robbins, Vonnegut, Bukowski, Kerouac, etc.... that for some could only have been that appreciated in our youth. They don't speak to me as a middle aged guy the way they did when I was younger.

If you read these authors (and the others which inevitably follow on a list of (certain) young guys favourite authors in the 90s)...

Who are the authors who define your 50s and 60s? What are the coming-of-middle-age classics? The ones that mean as much to you as as an 'older' person, the way On The Road spoke to many of us when we were young.