Gandalf a "steward?"

[Boromir88]

davem, oh I agree, if Aragorn had really just pulled an Arvedui and claimed Kingship, he may very well have been laughed out of the Court. He had to prove himself first and after Pelennor and the Black Gates, I think he gets the support he needs. Even after this, I think Aragorn understood how to play politics:

Faramir met Aragorn in the midst of those there assembled, and he knelt, and said: 'The last Steward of Gondor begs leave to surrender his office.' And he held out a white rod; but Aragorn took the rod and gave it back, saying: 'That office is not ended, and it shall be thine and thy heirs' as long as my line shall last. Do now thy office!'~The Steward and the King

This is Aragorn's first day as King, he really isn't well known to the people yet. It may not have been a wise mood to suddenly change a system that had been in place for quite some time. This shows Aragorn understanding realpolitik and why he was a "good King."

Boromir's situation of accepting Aragorn is a toss-up I think. Early in his writings, Tolkien plays with an idea of Aragorn and Boromir reaching Minas Tirith, and Boromir trying to kick Aragorn out of power:

Boromir and Aragorn (who notes a change in Boromir - who is keen to break off the chase and go home) reach Minas Tirith, which is besieged by Sauron except at back? Siege is briefly told from point of view of watchers on battlements. Evil has now hold of Boromir who is jealous of Aragorn. The Lord of Minas Tirith is slain (9) and they choose Aragorn. Boromir deserts and sneaks off to Saruman, to get his help in becoming Lord of Minas Tirith.~The Story Foreseen from Moria, The Treason of Isengard

Also as Faramir tells us in The Window on the West:

"It does," said Frodo. "Yet always he treated Aragorn with honor."
"I doubt it not," said Faramir. "If he were satisfied with Aragorn's claim, as you say, he would greatly reverence him. But the pinch had not yet come. They had not yet reached Minas Tirith or become rivals in war."

Throughout the journey (despite a rocky start) Boromir trusts Aragorn and seems satisfied with his claim. When he's about to die, he tells Aragorn to save his people, whether this was because he knew he was going to die and he thought Aragorn could be the only person now to save Gondor? Who knows, but we are left with doubt as to whether, if Boromir had lived, would he have resisted Aragorn's claim, would they have become rivals? And even more interesting, if so, what about Faramir? Anyway, just some question to stir some minds.