When I was a kid, I thought these were the coolest. I read the books over and over, but that's another thing entirely. The cover art just made me drool.
Some day I'll write a lament over Science Fiction, but right now I'm derailed again by looking at those books. That and the fact that 40 years later, those book covers still look vivid and fresh to me. I'm trying to think of the last time I walked into a bookstore and saw a cover that really captured my imagination like that. Probably not since I was a kid.