To get the best deal on Priceline, use the "Bid Now" option for hotels, rather than choosing a prepackaged hotel deal.
Select a city, number of rooms, and dates of your stay. Like any sane bidder, you want to bid the minimum $$ while getting your choice of hotel. Priceline incentivizes you to overbid, because if your bid fails, you must wait 24 hours to rebid.
Luckily, you can game the system using "free rebids." Priceline is aware that a small, dedicated fraction of their users do this, but they still make money.
To be able to rebid imediately (instead of waiting 24 hours), you must change one of: Your Hotel's Star Rating, the dates of your stay, or your City area. Even if you have the flexibility to change these factors, there's no need to compromise.
Priceline guarantees you will get a hotel with a star rating greater than or equal to what you bid for. In most cities, different zones have hotels of varying star ratings. For example, in Las Vegas, Zone Boulder Strip has 1 star to 3 star hotels. Zone Las Vegas Strip North has 1 star to 5 star hotels. In this scenario, if you choose a 4 star hotel and select Zone Las Vegas Strip North and underbid, your bid will be rejected and you must wait 24 hours.
But, you can add another zone, and bid in both Zones: Boulder Strip and Las Vegas Strip North. If your bid is accepted, you will get a hotel in Las Vegas Strip North, because Priceline guaranteed a 4 star hotel, and only one of your zones even has 4 star hotels: Las Vegas Strip North.
Now, you can continue to rebid instantly by changing the combination of zones you use. The only rule is that the combination can't have been used before, or be a subset of a combination you used. Let's say you want to live in Zone 3. If your bid for (Zone 1, Zone 2, Zone 3) was rejected, you couldn't rebid (Zone 1, Zone 3), because that is a subset of a previous bid. You could, however, bid (Zone 3, Zone 4) or (Zone 1, Zone 3, Zone 4) -- those are fresh.
Don't you wish there was a tool that would give you an ordered list of zone combinations to try, to maximize the number of rebids you get? Remember, the more rebids you have, the smaller the increment you can increase your rebid by. If your price range is $50 to $100, and you have 2 rebids, you have to bid in increments of $25 -- so you could overshoot the optimal price by $24. But if you have 50 rebids, you can rebid in $1 increments and hit the optimal bid on the dollar with no waste.
The tool you seek is below. Enter the zones you would actually stay in (acceptable zones), and zones that you wouldn't stay in (and that most importantly do NOT have hotels in the star level you want). The tool generates a list of the rebid combinations, in order to use (so you don't accidentally bid a superset of zones and throw away perfectly good rebids). Check them off as you go!