These hares were coursed last night but it is still in contention between the white and the red...
About whether or not Frodo is a sacrifice, sacrifices are victims and Frodo is not a victim. He doesn't just accept the Ring he grasps this errand with all his will and intelligence. It is less clear in the film, but in the book he is a much more feisty and courageous character, fighting, debating and standing his watches as one of the warriors should. He has indeed elements of sacrifice; he is very much aware he is sacrificing himself for his country. But that is not the same as being a sacrificial lamb, with no vote or voice. Frodo makes this fate his own by an act of will and moral courage special to the kind of individual he is.
Nor is he a martyr. Martyrs are passive and submissive. Frodo fights his fate, starting with a spirited attempt to refuse the Ring in that meeting with Gandalf in the Shire. When he assumes the task, it is also on his own terms, he decides all alone to go to Mordor without the others. Frodo also throws some curves; he scares the daylights out of Galadriel when he offers her the Ring, and she has nothing but admiration for him by the time he leaves Lórien. Befriending Faramir, sparing Gollum, Frodo uses his own wits, and cunning. He does not lie down under his fate.
When Frodo approaches Mount Doom his will, reasoning power and his strength are drained out of him till he seems just programmed to die, and then he does look like a martyr, but that is to forget the Frodo who brought himself to this, the bright strong intelligent hobbit who has not died - yet - but by his will took this path.
Frodo looks like a martyr on account of his suffering. He is wounded and beaten and knows every type of pain and terror. But despite all that there is an element of truth in what Elrond tells him at the start, that he will find friendship and experiences that are not evil. A holiday in **** maybe, but he finds love, not just Sam but all the Fellowship, even Boromir who betrays him. He is much loved. And he finds friendships that seem to make the word poor; with Faramir for example, whose gentle homage might have increased his sadness at the time but stands as the most beautiful passage of the book. And Frodo attains moments of enlightenment; Galadriel opens her mind to him revealing truths one feels she would hesitate to unlock even to her fellow Elves.
But above all sacrifice, martyr, are all stiff formal ideals, and Frodo is not to be tidily put into such a straitjacket. I have said he is an enigma, but not like a superspy, but like an ordinary person, with an unpredictable, messy life. He is like shot silk, changing colour in the light, till he seems different every time you look. Even his hair is untidy, and his baggy comfortable hobbit clothes. This is no allegory, myth, saint or stereotype. He is modern, relevant, an ordinary individual making an incredibly courageous moral decision for the good of all at a terrible cost.
He is the little man who with his friends takes on the totalitarian state and brings it down. Now, honoured but forgotten in internal exile his sleep is a nightmare return to those dungeons where he was tortured, and which he can never leave. But his days also are filled with the pain of the past, the burning cause which took his health, happiness and even his mind, suffering beyond enduring but desire beyond resisting, without which his days are empty and grey.
In this Brave New World, among these fit happy productive people, he cannot bear to live.