Functional bikes. Not Porn not Anti

Things I wouldn't necessarily take on a tour of somewhere where you're potentially going to have to do all the repair work yourself:

1. Aluminium frame, for all the lightness, if it fucks up, steel can be repaired by a random dude in a shed.
   
2. Internal geared hub. If that fucks up, you're fucked
   
3. Disc Brakes. (especially hydraulics)
   
   

Simplicity = king.

N.B. all my knowledge is from reported advice, I have never done a long enough tour to merit my own opinion.
frankly I don't have the patience.