I don't think I saw any, but have you tried looking at the Offers section accessible from the hotel homepage on SPG.com? You usually see this sort of offer there. And it may not appear in the regular booking page

Edit:

I just had a look, there's something called Sunsational Savings which is basically 4 for 3, inclusive of breakfast and an upgrade where available. Maybe you could crunch the numbers and see if that suits you. Might even consider an 8th day if they allow for consecutive discounted bookings.