I love watching chick flicks when I don't want to use my brain too much ^_^ (e.g. very late at night, or after a frustrating day etc.).
e.g. It's a boy girl thing.
I mean, I'm not a fan or anything, but they're good for when you're too tired to pay a lot of attention as you can miss half the movie, and in the next five minutes, you'll know what's happened during the bit you missed etc.
That, and I'm pretty easily entertained, so even if the acting isn't stellar, I'll be just fine.