I have only stayed concierge one time and it was at BWI-2005 Marathon-we had a great deluxe concierge room over the bakery, it was lovley and we enjoyed staying concierge for that trip.
We stayed at Beach Club 2007 Marathon week-end and really enjoyed it, was pleasantly surprised. I would like to stay on the monorail for marathon week-end in the future to avoid the bus transportation. Keep that in mind when you book your resort. It is particularly helpful to stay on the monorail if there are race spectators/cheer leaders in your group that want to scoot around property on race morning.
The resorts booked rather quickly this year for marathon week end. I can't remember exactly when they seemed to fill up but it was much earlier than I thought it should. Book early.