Starship Troopers is at the top of this list by Andrew Liptak at io9. It’s a tough one to do right. Much of the book consists of classroom lectures being received by the hero, and the hero’s thoughts on those lectures. I found them fascinating reading, but they wouldn’t translate well to the screen.
On the other hand, the novel also contains scenes of soldiers preparing for battle, and stirring battle scenes, which would film very well.
The movie has very little in common with the book. Indeed, the underlying philosophy of the movie, to the extent that it has one, is the opposite of the book. In the novel, Earth is subject to an unprovoked attack by monstrous aliens, and fights back. The novel is a celebration of that fight. In the movie, it’s never clear whether the aliens had provocation, and the Earth government is clearly corrupt.
Director Paul Verhoeven has said in interviews that the theme of the movie is that government is corrupt and betrays the nobility and sacrifice of its soldiers. Which sounds like a fine political sentiment, and one that any reasonable politically aware 21st Century American can support, until you realize that was pretty much exactly one of the themes that drove the Nazis to power in Germany.