This didn't fit the Manic Pixie Dream Girl trope in my mind. To me, those are always about the irrational life-loving weird female who suddenly invades the life of a boring overly-rational man, wacky hijinx ensue and he falls madly in love, rediscovers a zest for life before they inevitably discover that she's got her own emotional baggage hidden behind the carefree facade.
The only example of this that I've seen (that I can think of anyway) is the movie Something Wild, and you've just summarized it flawlessly.
"500 Days of Summer"
"Jersey Girl"
Those are good examples. Also:
Dharma and Greg
Eternal Sunshine of the Spotless Mind
Scott Pilgrim Vs. the World
Yes Man
When most people point out a Manic Pixie Dream Girl, it's a criticism of a bad plot trait. For me, that's not necessarily the case, 3 of those above movies are on my top list of favorite movies--I tend to like the Manic Pixie Dream Girl character, even while realizing that it can be overused. The part that makes each one interesting is how they differ from each other, and since the character is always one who prides herself on being different, there are always some variations.
Also, part of my like for the Manic Pixie Dream Girl is that Zooey Deschanel, my Hollywood girlfriend, has had quite a few of the roles, including 2 of those listed above in the lead female role, as well as playing a similar role in a secondary character in other movies like Failure to Launch.