Being 'close' to the regional event really isn't very important in this case since it's just a few hours long and all the possible things to do will be away from the regional event.
My suggestion: shop for the best value and drive 15-30 minutes to the regional. I used
www.hotels.com the last time I went to San Diego. As with
www.priceline.com, you've got to pay up front for your entire stay and I think a refund, if even possible, will take a lot of red tape with these discount services.
With hotels.com you get the price first. With priceline, I think you tell what you are willing to pay, then give them your credit card information and they'll respond if they can get the room. If they can, then you have already paid for it.