In an earlier discussion (both here and at TORN, I think), I suggested making Bilbo's first visit to see Smaug the climax of the first film. Let's see if I can find my comments ... Here we go:
Why Smaug's Death Needs to Wait for the 2nd Film
As has been discussed elsewhere, the indications from GdT are that the filmmakers are moving away from the idea of one Hobbit film and one "bridge" film, and more towards the idea of two Hobbit films, filled in with other information to a greater or lesser extent. It is unclear exactly how that will work, and in fact GdT has indicated that it continues to be a very fluid process. However, he continues to maintain that the second film will flow into the LOTR films, so that the five films tell one full story.
At one point, GdT indicated that the first film would end at some point after Smaug's death (but presumably not much after it). I have not seen any indication that he has backed away from that comment. However, I strongly believe that for a number of reasons it makes more sense to end the first film before Smaug's death. I believe this is true both from the point of view of making two films that both can stand on their own as well as being part of the full series, and from the point of view of adapting Tolkien work.
First of all, Smaug's death is NOT an important climax in the story of the Hobbit. It is, instead, an anti-climax. The two important climaxes of the story are Bilbo's first confrontation with Smaug, and his decision to steal the Arkenstone in order to try to broker a peaceful settlement of the impasse between the Dwarves and the others. To end the first film with Smaug's death (or soon after) would change that, making Smaug's death the climax of the film. Moreover, it would be virtually impossible to have a heretofore unknown and essentially unimportant character, Bard, be the one to kill Smaug as the climax of the film. That would make no sense at all. Far better to have the first film be all about Bilbo's growth from the comical, soft reluctant anti-hero that we see in the beginning to the brave leader of the expedition who confronts the ultimate evil (the Necromancer is a distant abstraction in the the Hobbit, and he should be no more than that in the first film).
Secondly, the second film needs to have a coherent structure. It can't just be the end of The Hobbit with a bunch of other stuff thrown in. Having Smaug's death towards the beginning of the second film achieves a couple of things. First of all, having a greater portion of the story from The Hobbit in the second film helps to make it that coherent story. More importantly, the filmmakers can use Smaug's anti-climatic demise at the hands of the minor character Bard to help facilitate the transition so that the Necromancer/Sauron becomes the evil focus of the second film (in contrast to the first film). This will enable the filmmakers to add material regarding the White Council (and perhaps even Aragorn) opposing the Necromancer/Sauron to the main storyline, so that the political intrigue involving the Arkenstone gives way to a major battle between the forces of good and the forces of evil that becomes in essence a prequel to the War of the Ring. Unless the battle of five armies is played down majorly, anything that takes place after it in the second film will seem anti-climatic. There simply cannot be a lot of material following the battle. Perhaps as much as was in ROTK following the destruction of the Ring, serving as a bridge to the LOTR films (perhaps ending with Frodo moving in with Bilbo). But no more than that. And I think that will be hard to do if Smaug has already been killed in the first film.
(Hmmmm, it might be worth combining these two threads.)
"Spirits in the shape of hawks and eagles flew ever to and from his halls; and their eyes could see to the depths of the seas, and pierce the hidden caverns beneath the world."