For literature I find 100 years of Solitude to be without equal. An absolute joy to read.
For nonfiction I have learned so much from 1491. It was recommended to me by a friend though I have never heard of it elsewhere. The premise is that basically everything we think about Native Americans before Columbus arrived is wrong. I could go on but here is one tidbit: we tend to think of Native Americans as peoples without government. Now of course there are so many different groups of peoples all over the Americas and across so many eras it’s foolish to even think of them as being this way or that way because who and when are you referring to? But there were many types of government. In fact the Incas were total bureaucrats! Anyway I’m doing a poor job selling it i know but it’s a great read.
For self-help try How to Win Friends and Influence People. I know the title sounds like it’s a guide to manipulation but it’s really not. It’s 100 years old but still holds up so well. Times change, but people don’t, you know what I mean? People 100 years later still appreciate it when you remember their name and look them in the eye and make time to listen.