We just did this-- we moved from San Diego to Bruges, Belgium, with us and four kids. Deciding what to move was much more difficult than we expected, and we didn't even have to get rid of everything we didn't bring with us. (We do plan to come back eventually, unless things really turn to shit there. My grown children are living at the ranch in the meantime.) We moved everything we thought we'd need for at least a year in one small PODS (7 ft x 7 ft x 8 ft, roughly 385 ft2) plus our suitcases.
We did use the move as an opportunity to pare down a lot of stuff that we were storing for no good reason. RatWoman and I are both hyper-organized but it's still amazing how much crap we accumulated without even thinking about it. Books, kid stuff, unused furniture, duplicate tools-- it all adds up, so fast, and without even realizing it.