I use Quikbook on almost every business trip I have to plan. Quikbook lets me choose a hotel by inputting my dates of travel and my price range. Even in larger cities, I can find a room in a really nice hotel for as little as half of the rack rates. For example, on a recent trip to San Francisco, I was able to stay at The Clift in a Superior King for $195 (usually priced at $350). Standard Kings were listed at $175; the only difference (according to the Clift's front desk) is 40 square feet of space.
the Hotel's Home Page
This may sound like a no-brainer, but many people skip this step. No matter which online service you use to book your hotel, check the hotel's official web site first for deals and discounts. Many list Internet-only specials that are not available anywhere else. It's prudent to compare the deals you get directly from the hotel before you book, although it may require a phone call to confirm availability. For example, I found a great deal on the Anaheim Marriott's site last summer ($325 for two nights, Disneyland park tickets for three days, free breakfast and $50 in dining credits). Although the deal is still on their site, I have not been able to book it again this spring.
You might think, with real-time information zooming across the Internet all the time now, that all of the online booking web sites would have exactly the same rates. Not so. In fact, I've often found vastly different rates for similar rooms at the same hotel on Travelocity, Expedia, and Quikbook. It's worth taking the few extra minutes to pull up the same hotel on a few different services and compare the prices.
If you are going to a popular destination like Disney World, there are a number of sites that can help you find the best hotel rates around. For example, MouseSavers.com lists the discount codes for Disney World as well as information on which online booking service has the best prices. (Check the Disney World section of this site for links.) If you're traveling somewhere else, Hotels/Resorts/Inns also lists discounts and special deals for hotels and resorts worldwide.
I'm not a big fan of Priceline, although I've used it a few times. I like a little more control over which hotel at which I'll be staying. However, it can come through with ultra-low rates in a pinch. Before you bid on any hotels, I recommend you check Bidding For Travel, a forum that can help you greatly increase your odds of getting a good Priceline value. Other travelers will tell you what prices they're getting successful bids on with particular hotels and cities. The advice there is invaluable and should always be your first stop before you place a Priceline bid. Also, be sure to see Beat the Bidding System for a few tricks to getting the most out of Priceline.