Alas Babylon is one of my favorite books! I read it first in high school. I still remember reading while walking from one classroom to another. There's also an excellent audio version narrated by Will Patton.
I've read this book (and listened to it) several times. I think the reason I love it so much is not the subject matter so much, though it had a huge influence on my becoming a prepper. I love how it shows that society can rewrite itself - how race was such a big deal pre-The Day and utterly unimportant after it. Same with gender. Now... this was written in 1959, so while it's extraordinarily progressive for its time there are still some holdovers when compared to how far we've come.
I also love the relationships of the characters, how they morph after The Day. This is one of those books that, if I ever win the mega-super-gicantor lottery, I would love to turn into a movie tweaked for today (Metropolis the musical is another, but that's a long story).
Anywho, if you're a prepper and haven't read this book you've missed one of THE defining books of the movement. It does go down the Eisenhower timeline from his Doomsday Book nearly in lock step. It also has a lot of good ideas and presents things you may not even have considered, such as sewing needles or shoes for kids or how diets become far less varied in subsistence situations. Five stars.