I think with a 7 year old and 5 year old you should be fine with any airline / route really. It all depends on personal preference whether you want to have a stopover or not. Make sure you have appropriate entertainment for them - personally I would take books, activity books, DS/Ipods/tablet/laptop etc and not be totally reliant on the inflight entertainment.
We have done the Australia flight with our children at ages 8 wks, 15 months, 24 months, and 5 years. The trip with my DD at 8 weeks was by far the easiest. But otherwise 5 years was fine - do be prepared for jet lag though although there's not much you can do to avoid it.