You've gotten good info so far. I can only add that there's wisdom on going with whatever you are used to. Shoe interface is a pretty essential part of the activity. Your first tour may not be the best time to go messing with it if you're already well used to one type.
Personally, I stick with SPDs as I have been riding with them since they were introduced in nearly 30 years ago. My body is just used to them and any other interface proves to be a distraction. I carry a lightweight, low bulk pair of regular shoes for off the bike.