Clefs d'Or members must sign an ethics agreement that forbids fulfilling illicit wishes ("tactfully decline illegal or unethical requests from guests") and conflicts of interest ("never accept goods or services from vendors for personal gain"), and some of the big–name hotel companies, including Mandarin Oriental and Peninsula, encourage their concierges to become Clefs d'Or members in order to further raise their service profile.

A Ten Point Primer: Advice from leading concierges on how to get the most from their services

1. Plan ahead. Call as much as a month before your arrival to discuss your wish list, including places to eat, current exhibitions and performances, and other must–sees.

2. Remember that concierges are travel professionals. They can plan itineraries, book flights, print boarding passes, secure visas, and switch seat assignments.

3. Ask for the moon, but have realistic expectations. After–hours tours of a museum, tickets to a sold–out event, or a visit to a famous chef's kitchen are all fair requests, although even the best concierges can't always deliver.

4. Take advantage of the concierge network. If you're continuing on to another city, ask the concierge to refer you to a colleague there.

5. Feel free to drop in. Most concierges will assist you with simple requests, such as a restaurant reservation, shopping recommendation, or theater tickets, even if you're not staying at their hotel.

6. Beware of reflexive responses. Some concierges are on the take, recommending shops and restaurants for kickbacks or favors. If a concierge offers only one suggestion, makes it too quickly, or doesn't probe you at all, ask for a couple of alternatives and run them by a concierge at another hotel.

7. Be specific in your requests. Rather than just asking for a good restaurant, specify the view, the price range, the cuisine, and the location you want. If you're in search of a souvenir that the destination is known for (say, ceramics in Portugal or silk in Thailand), mention that you're looking for quality and a fair price, not just the most convenient option.

8. Create a relationship. A concierge is more likely to go beyond the call of duty for guests who use a personal approach than for those who bark orders.

9. Remember that access has a price. Although the concierge is a good resource for last–minute event tickets, you'll probably still pay a premium.

10. Tip. Concierge services are free. That said, introducing yourself and offering a $20 gratuity at the start of your stay isn't a bad idea if you know you'll be making several requests. An additional tip at the end of the trip may also be in order.

The Tipping Point
When is a gratuity in order and how much is appropriate? Here, a few guidelines