A hotel site that we use from time to time to save money is Travel Pony (my link, feel free to leave your own in the comments). No one site always has the lowest prices, but Travel Pony is usually very competitive on the hotels they serve, especially when they offer limited time discount codes that stack on top of their other savings. Today they are offering $25 off a $250 hotel reservation using code 25OFF250, which isn’t too bad if you happen to need a hotel reservation in that price range. Note that the $250 total can be reached on a one night or multi-night stay.
Travel Pony also awards a $35 credit to new members to use on a hotel reservation of $200 or more. I can’t test whether that stacks with this $25 off $250 offer, but my guess is that it does not based on how previous discount codes work. However, the $25 off $250 does stack with referral credits you may have from friends or family members using your Travel Pony code to sign up and make their first reservation.
Remember that when you book via a third party site like Travel Pony you will probably not earn hotel points or elite status credit, so be sure to factor that into the overall cost equation. Sometimes the savings can way offset what you are missing out on by not booking directly with the hotel, but do the math for your own situation to make sure you are getting the best overall deal possible.