Wild Things is an interesting film. It is NOT a kids movie. Rather, it's in the cinematic tradition of works that are centered in a child's perspective but treat very adult themes. Spike Jonze accomplishes this wonderfully - not just in the action and the aesthetic, but the camera work, the narrative logic, even the soundtrack (or silences) are somehow very much based around what it's like to be a kid. Which - lest you expect sunshine and lollipops and the general idealized realm of youth - is not much fun. It's frustrating, confusing, and really kind of sucks.
Away We Go, on the other hand, is not about what it's like to be a kid - it's about what it's like to be in your early 30s, expecting a kid. Turns out to not be so different - confusing, frustrating, and just kind of sucks. Although it has its (sappy) moments. Being a kid does too, in Wild Things, but they're much more frequent in Away We Go.
Both movies are about quests, or at least voyages, and both resist a neat, overarching storyline, choosing rather to operate through a kind of series of vignettes. Although both achieve a kind of resolution, it's not really total, which is definitely a strength of both, I think.
A big difference is that Wild Things is much more abstract. It's hard to say what Max really learns or gains in the process, or even who the monsters "really" are. Away We Go, on the other hand, is much more straightorward and almost spells out the "message" behind each encounter. To me, this verged on hamfisted and caricaturish. On the other hand though, the main characters are more fully realized than those of Wild Things, particularly the father-to-be, who's definitely the most likeable person in the movie. There's more humor, definitely, but also more of a kind of sense of human-ness, and what people are actually like. It's not exactly normalcy or everydayness, because everyone is quirky in a rather twee way, but it is somehow realistic. Max and the monsters were less available - you didn't have as strong a sense of their personalities.
Ultimately though, what it came down to for me is that the bittersweet melancholy of Wild Things felt justified, whereas in Away We Go it seemed self indulgent and whiny. Even the scenes where they're having fun seemed fraught with potential tragedy (which was realized, more often than not). It's a similar kind of pessimism and anguished worldview as you find in David Foster Wallace, whom I also can't stand. Where everyone's like, "Oh, life is shit, it's so awful, but goddamnit the best we can do is grin and bear it and try to find some joy", which is an alright philosophy really, but the labor of finding joy seems like WAY more work than I really want to take on.