Yeah, I just finally saw this last night and was surprised that the vampires didn't even show up until at least halfway through the movie, and some of those shots in the trailer come from very late in the runtime. A really interesting movie to try to market, though, and I can see why it didn't find success overseas. Outside of the vampire angle, it is very specifically American in setting and subject matter.
My normal preference is that a trailer should focus on the first part of the movie up to and including plot point 1 (usually about 20-25 mins in) and leave the rest to be discovered by the audience, but the movie covers so much ground that it would be nigh impossible to do in this case. I would have taken maybe up to the first appearance of bad-looking folks with an evil glint in their eye to get the basic point across.