I probably should have mentioned that I was a teenager in the sixties, and what was available to me was the juveniles. I think my favorites were The Star Beast and Have Spacesuit, Will Travel, with Citizen of the Galaxy trailing not too far behind.

I think I only read Rocketship Galileo once, even though Nazis in abandoned alien tunnels on the moon seemed wonderfully extravagant. I reread it recently, and found it had so much immediately-post-WWII material as to be rather sad and grim compared to most of the juveniles.