Laketown is a very sound guess, and I think that was where it was supposed to end before they decided to have three movies. Have a look at the soundtrack list
here. It ends with "Out of the Frying Pan," referring to the chapter where Bilbo and the dwarves get caught in the trees after they escape the mountains.
Interestingly, a few months ago they released a sort of collage/banner of the major events of the first movie, and
that ended with the dwarves floating away in barrels. Then they announced that there was going to be three films, and the next time I saw that banner they had cut out the last slide with the barrels, leaving us with the dwarves in the trees. So that's why I think they changed things around with three films.