Great article. Haven't used Visa's concierge service yet (just got my first Visa Sig card a few weeks ago) but in the past I've used Amex's on a no fee card to book a impossible to get reservation for a restaurant in Paris.

They called back the next day with the reservation and I ended up having one of the best meals of my life. I wish I knew about how amazing concierge services were when I went to Peru to get a reservation at Chez Wong. Services like this are great when there are language barriers.