Something I learned a long time ago was that when working hard all day riding (loaded or unloaded) keeping my cadence at what my legs are happy at is really important to how my legs feel at the end of the day. Therefore shifting so that I keep my cadence and output force within a close range makes all the difference. In my opinion having less of a jump between chainrings is easier in this regard because as cycco explained well, you dont have to do the 3 or 4 up or downshifts when monkeying back and forth between two chainrings that have 16 or more tooth differences.

In terrain where one is shifting a lot because of rolling terrain, or constant steep up and downs, it is because of this that I appreciate a triple, just because there is less multishifting. I certainly contend that with modern brifters, multiple shifting is pretty fast, but its nice to not have to do so many quick shifts.

Think too of how a loaded semi truck has their gear ratios really close together, its the same with us--if we have a lot of weight on a bike--as I have said, going light in your gear really makes a difference in all of this but its very common for a lot of beginning tourers to have too much stuff.

I would really like to try riding a compact to see how a compact of maybe 16 or more tooth difference is with modern shifters, although I strongly suspect that I would tire of the regular 2 and 3 up/downshifts, especially if I have 30-40lbs of stuff.