(sorry if this is slightly OT, didn't know where else to post it)
My wife and I will be staying at a luxury hotel to celebrate a special occasion. In the lead-up to our stay, I've been talking to the hotel concierge by phone and e-mail and he's been extremely helpful in making dinner reservations at a place we couldn't otherwise have gotten a reservation.
Since I don't regularly stay at such hotels, I'm not sure what the etiquette is here. Is a tip for the concierge appropriate/expected? How much is appropriate? And, he will not be on duty when we're staying at the hotel -- how do I get the tip to him?