We let our girls stretch their legs - a couple of laps or so walking up one side and down the other is great, with a few minutes in the little wide sections at the back near where the kitchen/prep area is and toilets etc. LS is right though with turbulence sometimes being a problem - I was holding my DD at the time but another LO was wandering with her mum when we hit an airpocket. The poor little thing went cannoning into the edge of a seat and cut open her lip. Nobody was being a negligent parent, it was just one of those things, but still not nice to happen to her.

We've learnt the hard way that taking your own headphones for the kids is great, rather than using the plane ones which are generally way too big for their heads. The range of movies and cartoons for kids is incredible, and while it drives you nuts because they want to see bits of EVERYTHING, it does tend to keep them occupied. I also found that my kids napped even though it wasn't their nap time - the hum of the plane is great for that.

My biggest tip is for you and your DH to take a spare change of clothes (or at least a shirt) for yourselves as well as your LO. We've both had the pleasure of being covered in vomit from travel sickness, and if its 20 minutes in with no clothes to change into its soooooooooo ick.

Have fun.