We used Priceline.com's Name Your Own Price in August this year. We were 2 weeks before our trip to DL/SD and we didn't have many options. SD hotels are always so expensive, esp when booking last minute. I used biddingfortravel.com, and it indicated the Marriott La Jolla was accepting bids in the area we were bidding on and for the 3* rating we selected, and going bids were accepted between $106 and $110. Got it for $108, which isn't bad since the hotel website rate was $200+.
We were really happy with the Marriott La Jolla, with the exception of parking. You have to be prepared to pay a high daily rate for parking for most (if not all) of the SD hotels on Priceline. The Marriott La Jolla's daily parking fee is $20 - hefty, I know. But everything else was great with the hotel, right down to FREE guest laundry on the 3rd floor.
So when you bid, keep in mind that you have to pay for parking on top of your rate, and maybe even a resort fee (in the case of the Sheraton Carlsbad).