I second this, people should read topics that they enjoy - be it Nordic Noir or the classics, or Le Carre.
I'd also suggest reading more so in order to keep abreast of current events. Since most kids are more into digital than print, you could subscribe to the websites of the Economist, NYT, WSJ, Financial Times. Plus, on the free side, there are excellent websites on military-related matters.
But, keep in mind that, one, not everyone reads - adults and kids. His ALO might find reading a great hobby (I do), but not everybody feels the same.
And, two, some of our kids are doing a lot of reading in school and the last they want to do with free time is read a book.
Having said though, I'd recommend Graham Greene's The Quiet American, McMaster's Dereliction of Duty, or Max Boot's The Road Not Taken.