Look outside the box...not just the rate...
Instead of just looking for the cheapest rate...do a search with the Summer Promo codes and see if you can get a $50 or $100 bonus buck...then use the buck on your "extended" stay to get your $$ back...you may actually NET a profit.
I've stayed at Marriotts for as cheap as $79 and gotten the $100 bonus buck.
ChazDawg