Originally Posted by Often1

The concierge is the exception to the general tipping custom in the US. No need to tip for routine assisstance.

But, when the concierge lands you the tickets / table, etc. you wanted and haven't been able to locate, something decent is appropriate.

This is especially true if it's a property you routinely frequent and where you want a long-term relationship with the concierge so that you can call ahead and have them take care of things for you.