The deal is being promoted on the TravelZoo site through VistUSAHotels.com.
Since the best rate during the week at spg.com seems to be $119, this $99 weekday rate should be good for a Best Rate Guarantee claim.
The Best Rate Guarantee, which offers to match price and either beat by 10% or provide 2000 Starpoints as compensation (not to mention get you booked via the Starwood website for elite privileges), doesn’t apply to ‘package rates’ that include breakfast. So while the hotel offers a $69 rate without breakfast on weekends, and a more expensive breakfast-inclusive rate (where breakfast can be taken via room service or in the restaurant), there doesn’t appear to be a viable Best Rate Guarantee claim on the weekend offer, so to get it you need to use VisitUSAHotels.com.
$69 for a weekend night with breakfast would seem to make it worth popping out to the airport the night before a morning flight…!