Clint, I've booked using the marriott PC/CDP codes and got exactly the same rate including the inclusive LDW as without for an Icar. I did play around with a number of codes but could not get anything better. I guess my basic codes are not as good as yours !

I did infact save money with the code, as orginially I had a Fcar booked with a rate that excluded LDW. I now have a Icar booked with (hopefully) a two car upgrade to an Fcar for less money and LDW. (Plus a print out of the coupon incase of problems)