We have a room booked at the JW Marriott Grosvenor House in London using Marriott reward points for a week in May. It seems to be a nice property in the center of London. Can anyone tell me about it? What is the concierge/executive level like - I think there is concierge access 7 days a week. Also how easy is it to get upgraded to a deluxe room or a suite, since I believe they only offer a king bed or 2 twins in a standard room. Thank you for any help that you can give us.