I used Priceline for two of my hotels on our August/September trip. I had Motel 6 Maingate booked as a back up. Ended up with Red Lion for about the same price, and Marriott Suites for a little less.
As the PP mentioned, you can use sites like better bidding to try and work out which hotel you will get. Otherwise, just look at the Priceline map for the Disneyland area, and decide whether you'd be happy with any hotel in that area. The higher star hotels are generally further away from the parks anyway if that's what you're after, and they're relatively easy to figure out on Priceline because there are only a few of them. The really close hotels on Harbor are only 2-3 stars. FWIW, I was able to figure out I'd be getting the Marriott Suites, but not the Red Lion. They tricked me there though - I bid for a 3 star hotel and they 'upgraded' me to the Red Lion which is a 3 1/2 star.
I'm a fit, healthy solo traveller, so I'll be happy to walk 20 minutes or more. Also, these hotels are just for a couple of nights at the beginning and end of my trip. If you have young kids or elderly people in your party, or have some health issues that might be an issue for walking, I wouldn't suggest using any of those mystery hotel sites (unless you're willing to put a lot of research into figuring out which hotel you're getting).