Concierge is available at all the deluxe resorts -- it offers a higher level of service. You would have access to the concierge staff who can assist you in making PS - which can be a big help with harder to get PS's. You also would get things like continental breakfasts in the concierge lounges and light meals,snacks and cordials that are put out in the lounges throughout the day. Also things like the sunrise safari at AK are only offered to concierge guests at AKL.
To give you an idea what it costs, I called for an overnight stay in Aug. of this year just last week and was quoted $265 per night at WL (that's with a discount) for concierge so rack rate would be upwards of that -- I didn't book concierge as I was looking for just a courtyard view room for overnight. I've seen CL waterview rooms at BC for somewhere in the neighborhood of $375 per night around the holidays too.
HTH's