So, to his mind, it was up to Men. Actually I think this was his whole philosophy, that in this fight only Men were really suited to be players. Of Men, only he and Aragorn were there, and it seems to me that he was not yet willing to acknowledge Aragorn's rights as Heir of Isildur. So to Boromir, the only logical candidate to use the Ring, at the Council, was himself.
Fortunately wiser heads prevailed!
For the moment. Boromir doesn't have a plan, but I don't think he sees it as a closed book.
Is Boromir's motivation to bring honor and glory to himself (and maybe be proclaimed King?) or was it to save Minas Tirith with the honor and glory accompanying the completion of such a task being nice, but secondary to the saving of Gondor?
-Kevin