I really think the Marriott NLF guarantee is a joke. My experience with their customer service tells me that they are not bona fide in trying to keep the their end of the LNF promise.

If it is not because of Starwood/SPG and Marriott merger..I won't even bother with Marriott. I am just about to cancel on my remaining 6 stays with one of their hotel after encountering another lot of crappy service with their LNF agents.