You might consider reviewing the journals of on CrazyGuy as most expedition tourists use non-suss forks. I would also strongly recommend against going with anything but 26" wheels due to limited availability outside Europe and America. Not trying to sound rude, but I would only go with a steel frame, 26" wheels, with no suspension. If you are on a budget, consider a '80s or early '90s MTB frame and build it up from there. If you are in Europe, there are lots of manufacturers to choose from, notably Thorn (wide range of prices), Koga-Miyata, Roberts, and a couple of others. In the States, Co-Motion (pricey but nice!), Surly LHT (use only 26" wheels!), and Rodriguez can be considered.

Sounds like you are in for a fantastic trip!