The overarching Change I see in Frodo is his ultimate willingness to abandon the Shire and sail off to the Grey Havens. In The Lord of the Rings the Shire means everything to Frodo, and he (under Sam's influence) often reminisces over their good times there.
But Frodo has accepted a noble challenge from his old friend, Gandalf (who he clearly wants to impress), so he continues forward even while longing to go back. Even at the Council of Elrond, when Frodo volunteers to take the ring to Mt. Doom and destroy it, I think his tone and affect have in them a good bit of "this is what the Shire and Gandalf would have me to do, so I must."
In fact, I might even argue that Frodo is an active Be-er, and his ultimate Change, when it all comes down to it, is to Do the right thing for its own sake, rather than just for who it might impress or how it might benefit him and those he loves...
Finally: Indeed, bobRaskoph, "Sam, Gandalf and Gollum are definitely Steadfast." And glennbecker, the trilogy is such an epic, multi-faceted collection of characters and incidents, I too feel a bit "fuzzy" on all the storyforming implications!