The Marriott Champs Elysee does not have a concierge lounge. I was there on award about a year ago and received free continental breakfasts for my wife and myself (always did room service).

You just sign the check like you normally would, but it doesn't show up on your bill at check out. I tipped in cash. You might want to verify this upon check-in.

The only problem was that if I had the free breakfast at the hotel, I had to skip my morning pastry from the GREAT patisserie about a block down the Champs.