First, you need to understand that movies are not adaptations of books. They just use the book as a base. They should be assumed to be separate stories, because they usually are.
I think Lord of the Rings, The Shining and Hunt for Red October were the best examples of adaptation.
The most innovative was 2001 since this very long movie was based on a short story (Arthur C Clarke)
The worst attempts at adaptation, I think, are many of Stephen King's other works. Several of those movies only seemed to use the title of the book and not much else. Note: I loved Needful Things both as a book and as a movie that veers considerably from the book.
edited to add: I haven't read Shawshank Redemption, but I totally agree about the Starship Troopers by Robert Heinlein. I think you are right that the title and names of a couple of characters are the only thing the movie and the book have in common.