Larry Niven is a 70s hard sci-fi author who I'd say was the 70s equivalent of Golden Age authors like Asmiov. Not literary, but good stories and sci-fi concepts. I've heard that his later stuff sucks though.
A Mote in Gods Eye is a long and carefully constructed first contact story that is full of cool sci-fi ideas, mysteries with satisfying solutions, and twists that don't seem cheap wand would still be enjoyable the second time around. I think it would make a great series.