Tolkien said that Treebeard isn't nearly as wise as he seems. You know the bit when he refers to himself as the oldest being on Middle Earth? That was either boasting, ignorance or confusion. Tolkien specifically said that Tom Bombadil (there's that name again) is the oldest and wisest, and that Treebeard was mistaken. This was disappointing for me when I heard it, as I always thought Treebeard was the ultimate sage.
actually I think that kind of adds to the charm, sure he's not as wise as he may seem but he's still got that quark. That subtle arrogance, besides, wise or not, I found his affection and loyalty for his fellow ents endearing.
I honestly have a hard time understanding Tom Bombodill. Granted I read the LOTR books many years ago when I didn't have the anolytical abilities I have now, but, while I didn't think Bombodil was a bad character, i didn't find him that interesting, he kinda seemed like a quarky woodsman to me. Admittedly the only part of that character I remember at this point is from the Fellowship of the Ring where Frodo meets in him the woods. I don't remember him appearing anytime afterwards.
of course, err.....it may also be because I never got around to finishing Return of the King, I WAS BUSY OKAY, I'M SORRY, I'VE SINNED!
I should really go back and reread those