Woulde fully agree with PAXBOY re USB stick a true god send when you have a large number of docs. As for routing the world is your oyster pick places you want to see on route and go have a look !. I would try to keep to one carrier to get air miles for next trip but that is just my view and I know other disagree. However Africa / Far East / Oceania great places to explore. Would personaly not bother with routing back through Canada as it is (and I say this with due care to the many Canadians I know) "similar" to the USA in many respects.
As for length of flight I would try to limit to max of 5- 6 hrs in one hop in the back but you may have to stretch that in certain areas.
If going by sea I think there are some Cargo ships you can still get rooms on which for me would be more intresting than a cruise ship option, however with kids in tow this I admit would be difficult.
Look forward to hearing the route you chose and have a good trip.