I just went to the Amsterdam Marriott site and looked to see what would happen if I tried to book a room using points. There is the paid Executive Lounge upgrade option. Platinum and Gold have Lounge access anyway and possible upgrades to Exec Lounge rooms, so the paid upgrade is probably for a guaranteed Exec. Level room or for Lounge access for those who aren't gold or plat. For instance, we were at the Amsterdam Hilton one night (we spread our business around this trip) and since we don't have Plat status with Hilton the only way we could get Exec Lounge priviledges was to pay a 75 euro upgrade fee (since it was for one night we passed on that option).