When we had our home's roof replaced we had the barns reroofed as well. They too had been cedar shake and were clearly in need of replacement/repair. For all of the same reasons that helped us decide to not use cedar on our home's roof, we decided to not use it on the barns as well.
Instead, we used standing seam metal. In our travels this past summer, we saw hundreds of barns dotting the landscape and my very favorites always had metal; especially raw or galvanized metal. I also liked the idea that sense we would no longer have the same roof material on all of our buildings, they would at least be the same color(ish).