I can't comment on whether a particular Marriott resort meets your definition of "luxury" or not, but you can easily see a list of all the hotels that Marriott considers a resort in the US: US Marriott Resorts

I haven't been to all of them, but I have been to the Fort Lauderdale Marriott Harbor Beach Resort & Spa and like it a lot. I do believe that Mr. Marriott, himself, also likes that resort and supposedly vacations there every year.