Lots of people seem to want Frodo to die.
But after reading exa's post it seems like Boromir IS the only member of the fellowhip that should die in the story.
And he does seem like the most obvious choice. And no doubt if any of the other characters died...it would change the rest of the story dramaticly.
But perhaps it is the TIMING of the deaths that would choose wheter it be fitting or not.
True that Gimli's death at Amon Hen would seem like an unwanted character...easily exited to make room for more 'important' characters. But what if he had died at the black gate instead?
But at the TIME...Amon Hen, at the end of the Fellowship of the Ring, Boromir is the only choice.
Had Merry been killed...the orcs might have taken SAM and pippen. Leaving Frodo to defend for himself. And even altering the paths of Rohan -Theoden, and Eowyn.
Had Aragorn been killed, Merry and Pippen would have been abondoned to torment and death, leaving legolas and gimli...following frodo, or just going back to their own lands.
But everything happened for a reason. and if any of these events were altered or changed, the outcome and ending would be very different.
The lives and even deaths of each character, are what drives the story of the 3rd age.