A couple of years ago, I picked up "Have Spacesuit Will Travel" for my son. He wasn't ready for that level of book, but I reread it. That started me reading SF again for the first time since I was in my teens. There's a lot I missed over twenty-five years (Card among them), and a lot I missed from the 1960's - Phillip K. Dick, Roger Zelazny, Clifford Simak, etc. It's amazing how much more I appreciate now that I am older - "The Martian Chronicles" and "The Moon is a Harsh Mistress" were enormously dull as a teen, but compelling as an adult. Try "Old Man's War" it is a science fiction novel by John Scalzi. It is more mature than Starship Troopers so please don't just give it to your son until you have read it first.