Here's a classic: Ringworld by LarryNiven, the 3rd Novel to win both the Hugo and the Nebula awards (there have been a few more since).
I feel that the ‘Hard SF’ tag is rather undeserved, but ...
... These were collected by Ellen during her time as editor for OMNI – a good number of the stories included in this volume she turned down for the magazine for being too raunchy. Besides the LarryNiven ...