While I love all of C.S. Lewis’ works (and yes, “That Hideous Strength” is close to my favorite book of all time), I went with “The Problem with Pain” even over and above “The Great Divorce”.
The reservations I have about “The Screwtape letters” would be that they are best suited for either the least informed or the BEST informed person, not for Joe or Jane Average. The “less informed” would be more likely to want to learn MORE about Christianity, the “better informed” would be more likely to appreciate the more subtle insights in the book, but the average person would read it, enjoy more or less while reading, and then forget about it.
“The Great Divorce” is very powerful but the imagery (and don’t even get into the, <but isn’t it Purgatory rather than being either heaven or hell for all time> conundrum) can be confusing, especially to non Christians. (I love it anyway though).
“Mere Christianity” was prepared, I believe, originally for radio programmes, and so there’s a certain “sound byte” quality that might work well with the average person’s shortened attention spans. But some of the imagery doesn’t date well, and too much of it will be sidetracked by the eternal, “yes, but. . .” argumentative “seekers” of the current times.
“Miracles”, C.S. himself said, I believe, that he regarded as more flawed in later years. I think too many people would approach it expecting much more (or much less) from the title alone. And while I like it, it has the same basic flaws as “Mere Christianity” with the “yes, but. . .” factor.
I have to re-read “A Grief Observed” as that one is less familiar to me.
One you missed that might be interesting, especially to the “historians” out there, is “Till We Have Faces.”
I just finished re-reading the Chronicles to my youngest. Her favorite? Prince Caspian.
