I would tend to credit to VS in this scenario because there are more sweet spots (for now) and you have the ability to top off with CC points (and from time to time they have transfer offers to VS as well). The addition of ITA (for now) to VS redemptions makes IAD - FCO a potential sweet spot (pending the ITA/Lufthansa tie up and potential for ITA to become *A in the future) and of course NH continue to be a sweet spot for VS although it has gotten more expensive and the availability has dried up