[Pitchwife]

Interesting, especially your comparison between Sauron and Bombadil. In a way, Bombadil could be seen as Sauron's precise antipode, much more than even Gandalf. In my opinion (based on Eönwe's long post in the pertinent Chapter by Chapter thread), old Tom was immune to the lure of the Ring because he simply didn't care about power and its use for bulldozing reality (to use one of my favourite phrases from Tolkien); he was content to be his own master and let other things be what they were, even Old Man Willow. Sauron, on the other hand, cared about nothing else than power and bossing others around - hence his vulnerability to being deceived by his own creation (what a complicated way of deceiving yourself!).

I don't think, however, that there was anything left in Sauron that could feel grateful to the hobbits for saving him. (Saruman, maybe - his spirit turned west for a last time before it dissolved with a sigh, whereas the last gesture of Sauron's shadow after the fall of Barad-dûr was a futile menace.) I can't see that Sauron was saved at all in any way - rather he lost both his power as a tyrant and the light of Valinor.