Depends on how you want/need the flight to go. Do you need to keep an eye on them, do you want them to sit together (will that help them pass the time or will they get too excited), and do you want to sit with your wife?
If you need to keep an eye on them at the front, they'll have to be in row 1 with you in row 2, and you can't really converse with your wife in 2AK.
If that's important, you'd be better off across row 5 (next best row 4), adults in the centre; or put your 12 year old one window forward if they'll want to occasionally interact (K+K better than A+K).