Go to the pound shop and wrap everything up. Keep a couple back for absolute emergencies to avert meltdown in case you see one brewing. Suspend normal rules and pick your battles but keep the golden rule of 'no annoying other people', otherwise you'll drive yourself crazy trying to do 'normal' in a strange and exciting place. Do you have a phone that plays videos? If so load up some cartoons or take an ipod or similar with kids stories on and invest in some suitable headphones for her.
Make nappy packs with a nappy, a few wipes and a nappy sack in a freezer bag, and keep one in your pocket all the time. It makes emergency nappy changes so much less stressful than lugging the whole bag to the plane loo.
Pack lots of little snack pots and let her snack little and often. Better for digestive system while travelling and also can be produced as a distraction.
Pack a hand towel in your hand luggage. Serves as a pillow, shade from the light, cover for a secret den, blanket, peekaboo, hide and guess game, and if all else fails you can mop up things with it :o
Drink lots from the trolley :)
Have a lovely trip