We went to Croatia with our ds last summer when he was 11 months old. We took a couple of new toys for him on the plane, as well as a couple of books and a couple of old favourite toys, and the best tip is to give them to her one at a time so she doesn't get bored.
As for packing for the holiday, I think we prioritised the wrong stuff.
We took huge amounts of stuff for him with us, probably went over the top, and ended up not using the masses of jarred food we lugged around as he was quite happy to eat lots of fresh food (the chemists over there were stacked up with Hipp Organic too). We also took loads of nappies, which seems really stupid now, seeing they're pretty much universally available!!
The thing I'm really glad we took was a supply of his favourite formula cos he didn't like any other brand. Oh, and stacks of suncream and a blanket from his cot at home as a comforter!
We spent ages searching for an open chemist late one night to buy a thermometer, Calpol and rehydration medicine, cos he got an upset stomach at one point, so I'd suggest taking those with you too.
Enjoy!