How old is she? I fly often on my own with a now 4, 3 and 11 month old. I have been doing it for almost 3 years now. Some things that help me...

Sticker books are great as the kids can't draw on things they shouldn't. Likewise those magic markers that are clear and the colour appears on the page are good.

Like OP said books are heavy, they also don't provide entertainment for very long, unless they are the ispy type ones, so i prefer to tell them a story. i make up things and get them to help.

I make a puppet out of the sick bag. We play eye spy, they eye spy books are great. i wrap a small toy in wrapping paper, if it was a long flight you could have a few. We sing songs, tell stories and look for fairies out in the clouds?!

The girls use my iPhone, or their leapsters. They are too short to see the TV's unless we get a bulkhead seat so i sometimes take their portable DVD player or my laptop. I don't allow the kids to walk around much unless they need to go to the toilet. This is mainly because it is hard for me to control them while holding a baby and i also don't think it's fair to disrupt all the other passengers. i find it works best for us, my kids are super active too, but i kind of just treat it like a long car drive, seat belts on unless going to the toilet. If i let them walk around just once, then they would expect it all the time and it would make my life much harder. It sounds a bit mean, but it works well!

Make sure she has requested a childs meal, if you don't they will often just get a regular adult meal.

A sippy drink cup, dummy, bottle or lolly pop help with the ears when taking off and landing.

One thing i do struggle with is the toilet. When i need to help the toddler while holding a baby can be a challenge, but i usually find a hosty staring up the back who is more than happy to hold a baby for a few minutes.

Lastly if she wants it you can request assistance. They will get someone to help you on and off the plane. I try and take as little as possible in the way of hand luggage so i can wrangle the kids myself without asking for help.

How long is the flight?