The healthy vacation rental homes in Florida are either empty from the oil spill on the west coast or booked from the overflow to the east coast. Discounts don't solve either challenge.
Rental restrictions on vacation homes and holiday rentals in Sedona, AZ means the only deals you're likely to find require a 30 day stay. If you can afford to take a month off, you probably don't need a rate special!
My current favorite site for good prices on vacation rentals is FlipKey.com With airline prices rising, I'd grab the lowest rate. In these times, it may be more important to look for a home that isn't in foreclosure than it is to get a rate special.