Childhood's End? Sounds sad - what's it about?
It's about a race of aliens that help the people of earth.  But, they never describe how they look until the end.
Ohhh, nice. We could definitely use the help, especially now! I like how they're here to help us instead of decimate us - unify earth, eliminate poverty, AND end war? Don't threaten me with a good time!
Yes. that is the basic story.  I won't ruin the ending for you.  What are your favorite sci fi novels?
Well, I'm a big anime fan and there are tons of sci-fi stories...I used to read Dune and others when I was a kid, but it's been a while sadly. Not sure if they have a Firefly novel out there, though I assume there's at least a ton of fan fiction...but I'm partial to space westerns typically. But if I had to choose, it was would be the Dark Tower series by the King...
I started the Dark Tower series once, but it just never grabbed my attention.  I did like The Stand though. That was my favorite of his. 
Yeah, Dark Tower is sort of long, and it's confusing at first, hell, even throughout, but there's just too much good in there to miss. I encourage you to read it. I don't recommend the movie adapation, even though I love Idris Elba. The Stand on the other hand, is of course a classic...I heard there was a "continuation" written for The Stand since Stephen King didn't like the ending or something...or maybe he created a new ending for the series in the 90s...
I hadn't heard about any 'sequel' to The Stand.  Any idea what the name was?  I didn't really like the ending either. 
Apparently, King wrote a "continuation" to the book for CBS All Access Limited series...I guess that was in 1994 (it's unclear based on what I can find). But yeah, apparently there is a new ending written by King himself. I guess it was just 9 episodes and he wrote the last ep...apparently, they share what happened to the survivors at the end of the book too.
So it wasn't something published in book form.  Just part of the movie/series?