Asimov's original "Foundation" - it's effectively a collection of 4,5 short stories. I recommend to remain at a discreet distance from the rest of the series. While good within the universe, they are ... different.
"Ender's Game" and "Speaker for the Dead" by O.S.Card. (Do not touch Xenocide without a hazmat suit. And if you do, burn it before reading.)
"Snow Crash" by Neil Stephenson.
"Rendez-vouz with Rama" by Arthur C. Clarke.
If you're up for some thought-provoking stuff, "Stranger in a Strange Land" by Heinlein. Not the easiest read but your carve-out basically rules out "The Moon is a Harsh Mistress".
One of my favorites is based on a similar premise, Pushing Ice by Alastair Reynolds. I like most of his work but for short stand-alone stories this one stands out. Reynolds works are hard sci-fi, mostly sticking within the known laws of physics which present some interesting problems for the characters.
"Ender's Game" and "Speaker for the Dead" by O.S.Card. (Do not touch Xenocide without a hazmat suit. And if you do, burn it before reading.)
"Snow Crash" by Neil Stephenson.
"Rendez-vouz with Rama" by Arthur C. Clarke.
If you're up for some thought-provoking stuff, "Stranger in a Strange Land" by Heinlein. Not the easiest read but your carve-out basically rules out "The Moon is a Harsh Mistress".
"Embassytown" by China Mieville.
EDIT: I forgot "Hyperion" by Dan Simmons.