Concierge service gives you upgraded amenities and toiletries which vary by resort. Bathrobes to use during your stay and evening turndown service are always part of it though. Also you get private check-in, and preplanning assistance. They will help with any other requests that you have before and during your visit. And you get continental breakfast and snacks during certain times of the day.
Bascially you pay for a higer and more personalized level of serice. The cost is generally $100-200 per night over and above the room rate, and only available at deluxe resorts.
Anne