I'm trying to remember what else the writers did (Sweets from Bones being one of the writers).
Now I like Ed Helms, I like Christina Applegate, and I like the Vacation movies... but somehow I feel like... this could have felt much more unique. I mean, what made the old National Lampoon movies great is that the scenes all seemed to be inspired by true stories, just cranked up to absurdity. This flick (and to be fair, Vegas Vacation, which I actually kinda like) feels like it's just "a movie about a vacation."
I feel like you need that grounding in reality in order to make this feel right, and you just don't get that feeling from this trailer.