What type of roads is the OP expecting to ride on for the majority of the time?
I have opted to fit Schwalbe Duranos on our new touring bikes simply because we have had excellent experience with them on our tandem, and because the majority of our touring in the near future will be on sealed roads. They are relatively light, have the "puncture-proof" band under the tread, and handle pretty well.
I've had the Marathon Plus, and would consider them for a mix of sealed and gravel road touring.
I've had Vittoria Randonneurs over quite a few thousand kilometres of touring and commuting and they were good wearers, but I felt they were not good enough to ride on loosish gravel as you would get on the crown or at the sides of gravel roads.
gamecock, I think your LBS is BSing you on those randonneurs.
I used to be a confirmed Conti TT2000 fan, but when they went out of production, I moved on to the Randonneurs, then Conti Gatorskins because I was doing a lot of LD riding.