A year or two ago, I had a reservation at the Bethesda Marriott for a week to attend a course there and got one of these 'virtual concierge' emails. I replied that I would love to be upgraded to the concierge level if space was available, but as a lowly Silver, I never thought I'd get upgraded. Sure enough, the concierge sent me a nice reply, telling me that I had been upgraded (at no additional cost, they honored my original rate, which was the gov't rate). I was very surprised, and always make the same request now, but have never had success after that time.

AGS