For SPG, on late Tuesday afternoons or Wednesdays, check out the "Starpicks" for that week, in your area. I've found plenty of rates within your ballpark on this...including recently at the STL Westin and was able to see why it gets consistently awesome reviews--while racking up an additional stay I needed. It changes weekly, so just bookmark it & check back if your area isn't listed.
http://www.starwoodhotels.com/promot..._HP_STARNEW_NF