The kids will have a ball just make sure you have headphones that they can actually use on board an aircraft and lots of sweets and nibbles. Over the summer I did a mini TP run stopping in JFK before heading to KOA. the break was great for everyone and they all got a shed load of TPs and Avios. My kids have never flown Y or WT long haul and are in for shock when it happens. They are big fans of AA, CX and QR due to the seats.
When very young they were traded like royalty by CX and QF.