That depends on so many things! I'd say, use whatever you are most experienced with. Predictibility is a great virtue when taking an adventure like this. I like color negative materials, (though some have very valid opinions otherwise). Kodak Gold is not bad stuff! Refrigeration may be problematic on a trip like this, so I'd personally stay with a "consumer" material rather than a "professional." I'd also think about getting the processing locally, avoiding the airport X-Rays. [Anyone have experiences to relate?] Sounds like fun. Can we come along?