Hi John & Ruth!
Just listened to the latest podcast and you've twisted my arm into joining your community. I like Google Plus, but I sometimes feel I'm not putting enough into it. I have used it for a couple of MOOCs that I've been following where it has been useful for discussing things with other students - one on Mathematical Thinking on Coursera and currently one on Web Science on Future Learn.
I'll throw a quick app recommendation at you, which I think your kids (or you!) might enjoy.
Hatch is a virtual pet thing, similar to the old style tamagotchis but with lovely animation and sound. You don't really do much other than feeding different fruits to your pet, cleaning up after it, buying it rugs to sit on and finding various ways of interacting with it. One nice touch is that if you play some music and then start the app, your pet will be dancing to it. You can also buy a camera which will randomly insert your pet into real world pictures that you take (if that makes sense!)
Probably the best thing from your perspective as parents is that there are no in-app purchases. All of the in game currency for buying things (acorns and stars) is earned by selling fruit to the shop keeper, finding hidden coins on the screen or by making your pet happy. There are no irritating pop-ups selling bundles of coins for £69.99.
It's currently £1.49 on the app store and I've enjoyed playing it for the last week, and I suspect you will too.https://itunes.apple.com/gb/app/hatch/id718835727?mt=8