Kim Stanley Robinson 

The Three Californias 
-
three different visions of the future of Orange County

The Wild Shore
(1984)

The Gold Coast
 
(1988)

Pacific Edge
(1990)

I really marvelled at the imagination that could come up with three alternative futures: A nuke, a material society, and a Green society. 

I wanted him to put some endings on them, especially Pacific Edge.

Mars Trilogy 
-
from first settlement through terraforming

Red Mars
(1993)

Green Mars
(1994)

Blue Mars
(1996)

One of the great sci-fi trilogies, its epic sweep covers centuries of change on Mars, on Earth, and in the characters and their families. Red Mars won a Nebula, Blue and Green Mars won Hugos.