Most large hotel chains have a best price guarantee which states the hotel's official website will have the lowest advertised price you can get anywhere else (e.g. expedia).

But, non advertised prices can be lower such as on Hotwire, where you don't know which hotel you are reserving, you only get to choose the price and have to stay wherever Hotwire makes the greatest margin.

If you do find a lower advertised price for a specific hotel, you can usually call their 800# and get it price matched and something extra.

http://www.marriott.com/hotel-prices/travel.mi

http://www.starwoodhotels.com/bestrate/index.html

http://hiltonworldwide.hilton.com/en/ww/ourbestrates/guarant...

http://www.hyatt.com/hyatt/specials/offers/offer-details_hot...

https://www.ihg.com/hotels/us/en/customer-care/lowest-intern...