Interesting - I had two intense years of reading SF in my mid-teens but have only dabbled since. I read all four books you mention in that period and can remember them all vividly, whereas most of what I read at the time has long since vanished from my mind, particularly by writers of Clarke's generation.

Oh, and I remember A Fall Of Moondust too. It struck me then and now as the great mass-market novel and movie that never was.