The Watchmen by Alan Moore and Dave Gibbons
1 Corinthians 13:11
“When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put childish ways behind me.”
When you ask yourself why I included this book in a Kryptos focused list of books that will be predominately about cryptology and the CIA – go read it. When you mention that you saw the movie, shut up and go read it. When you say that you’ve read it but haven’t read all these boring other books with no pictures then shut up and go find one that talks about anything from the 50’s to early 90’s.
Many other and finer folks have given quality analysis of this graphic novel which I won’t even pretend to be able to attempt. Let’s just say it would be handy to work through it and have these types of symbolic elements rattling around in your subconscious.
Will it help you solve Kryptos? Probably not but it will help you understand Kryptos when you have solved the 4th part and anything remaining.
Final word? This will add depth and color to your perceptions of the world and the context of the CIA.
Bonus fact: The Comedian was inspired by G. Gordon Libby
Kryptos - Beyond K4 
I was lucky enough to be exposed to this while in college. Young enough to not be afraid to go into a comic book store once a month, and old enough to appreciate the feeling of ” holy crap, I can’t believe they’re selling something like this in a comic book store. I slipped the first 4 issues to prof. Kalin in a Manila envelope like a secret dossier. Check out Rorschach, I said. Behind you.
Experiencing it in serialized form was amazing. It was like a virus that swept through the art, soc, psych, phil, and eng; claiming its victims from the hardiest and elite.
Anyway, I agree with your assessment. At the time as a young intellectual, just reading it made you feel like you belonged to a secret society and it was coded and hidden in such a way that it only attracted attention from those who could appreciate the beauty of its design.