There are some properties within the Marriott universe (now or in the past) which have offered the multiple day option either for a time or for many years. The two which I recall are the San Juan Marriott Resort & Stellaris Casino (when I was there in April 2004) and the former San Francisco Renaissance Parc 55 Hotel (when I last stayed there in 2006, but hotel is no longer affiliated with MI). I have no recollection about which ISP each hotel used, but I remember in each hotel the number of days desired was chosen at the front desk, at time of check-in. Both offered a choice of up to seven days, San Juan without multiple day discount, and Ren Parc 55 with multiple day discount. I do remember a couple of limited service properties which offered a two or three day option, but can't remember where they were located.