I think the common reference is "Foundation Series", after the title of the first book.
Prelude to Foundation (1988)
Forward the Foundation (1993)
Foundation (1951)
Foundation and Empire (1952)
Second Foundation (1953)
Foundation's Edge (1982)
Foundation and Earth (1983)
I really didn't like to read fiction until I read this series. I read Foundation and Empire first, then Foundation and then Second Foundation, since I did not know that there was a series/order. I read the book as part of my English (literature) elective in high school. I also read Heinlein's Glory Road and Bradbury's Fahrenheit 451. I read the prequels then sequels about 5 years ago.
It was interesting to read the Foundation series at the time (~1974, with the backdrop of the US and Vietnam War), since I could see parallels in world. It was also interesting in the role of nuclear technology, which was understandable given that Foundation was written in 1951, and many people had unrealistic expectations of nuclear energy.
I think the Foundation series would make an awesome SciFi movie - but only if done right. Unfortunately, what appeals to me (the plot and characters rather than action) would probably not appeal to the masses.