Christina, I was really glad to read your post because I agree with your remarks and my discomfort is similar to yours. I think that's why I started this thread.

I don't want to be thought a cheapskate, and I am comfortable tipping the bellhop and the maid (although that's another story I'll probably start another thread on), but tipping the concierge seems like a much grayer area. Obviously from the replies here, people vary greatly on what they think is appropriate. So maybe it's one of those awkward situations one just has to live with, do your best, and muddle on.

Our particular situation was made more confusing by the lack of a single person who was the concierge. And I think we were awkward about it because we never use concierge services. Making these 2 restaurant reservations in Paris was the first time I can remember doing so.

But this thread has definitely made me feel ok about what we did do. It's not like 200 people wrote in to slam me for not leaving twice as much of a tip.

I would agree that if they are going to extra lengths, a gratuity would be in order. On our last trip the desk clerk argued for us (in France) with our German car rental because our battery went dead and we were on our way to the airport to fly home. He gave us some suggestions which got the car going, came back to the hotel to get the luggage and could not shut it off for fear it would not start. In the race to make the plane, never did leave him a tip, he even helped load our bags. We are going back this fall to the same place and hope he is there to finally thank him.

I also wanted to see if Rick Steves had any thoughts. He does have input on his web site from people who reside in various countries. Although most do not address concierge service, some refers to assistance and it is interesting the differences between countries.
If you are interested check out:

http://www.ricksteves.com/news/0208/eurotips.htm