I wish he were still alive, too. As a kid, I didn't think about it so much, but when I read the Space Trilogy I was in college, and I felt like I wanted to ring him up on the phone and discuss it; it seemed like he would have really had interesting stuff to tell me...of course, he was a bit of a grump and might not have wanted me ringing him up, even if he had been alive!
The humanist author Alduous Huxley also died on that day JFK and CSL died, and Lewis expert Peter Creeft (Kreeft?! I forget) has written a play about their simultaneous arrival in the afterlife which is quite insightful about the views of all three, as they discuss what happened to them and where they might be.
Seems like they are in utter darkness for most of the play as they discuss their lives and philosophies, then comes a moment when CS Lewis calls out for the others to look at the bright, beautiful light which is dawning -- the corrupted Catholic JFK says he believes he can see some sort of light barely flickering in the shadows, but sadly, atheist Huxley can see nothing but the darkness...
It reminds you of the dwarfs at the end of TLB who cannot see they are in Aslan's country, so it's a nice tribute to Lewis.