Yeah, we decided to simply take the kids out of school for a couple of weeks. The way I see it, seeing the world has as much educational value as school.
I remember that my high school had a similar view when they organised a central Australia trip when I was in year 10. There was 30 of us out of a school of 800 who went on the trip (no pre-req with grades, just pony up the $$$), and we missed a week of school to do it and no they did not provide us lessons / homework on the bus / plane in it's place, they figured the educational experience of travel was the perfect classroom / teacher.
Since then I see nothing wrong with taking the kids out of school every so often (say a week or two a year) for the purposes of travel.