I find that the works that tend to make the strongest impression, for good or ill, are those consumed in youth; for me, the book that sticks most persistently is The Amazing Adventures of Kavalier & Clay, which I had the fortune to randomly purchase for $4 at a Barnes & Noble sale not knowing a thing about it other than that it had a neat comic booky cover. I read it at a particularly miserable and friendless time in my life - halfway through eighth grade after transferring to another school district and, even worse, after my obnoxious teen hormones had kicked in - and it was sort of 'my' Catcher in the Rye, or substitute in whichever coming-of-age novel worked for you, in that it gave me perspective on my life at the time as well as that irreplaceably engrossing outlet for empathy that novels alone of all art can provide. It doesn't hurt that I found it beautifully written, either, though I sometimes wonder if I wouldn't find the prose a bit purple if I dared revisit it now.
I also have a peculiar attachment to 20th century memoirs written by pilots, namely the trifecta of West with the Night by Beryl Markham and Flight to Arras and Wind, Sand, and Stars by Antoine de St. Exupery.