We took DS Sydney when he was 8 months. He was just like you described your DD, more interested in crawling around and not really into toys. Obviously the flight was a bit shorter than yours will be but I bought him a new toy with lots of touchy feely stuff that made lots of crunchy sounds etc and that was pretty handy and seemed to engage him more as he'd never played with it before. Other than that he was quite happy to just watch everything going on around him, the flight attendants always gave him a bit of attention when they walked passed. If he was getting a bit restless I'd give him an arrowroot bikky and that would keep him occupied for a bit he he'd forget why he was whinging in the first place. So yeah you can't really be feeding her the whole time but food is a good distraction if she gets a bit irritated.