They know by your member parking permit in the window. I did have one ask me if I was a member when we stayed at BWV last December. I was happy with the valet service last December, they were always quick. We called from our room and by time we got to the lobby it was there 2 of the 3 times, the other time it was just being pulled up (granted, our room was down near the fountain so it was a long walk). When we dropped off, they came up quick to take it. I don't mind tipping when they do a good job.