coming from a guy that travels 100% ... as in over 300 nights in a hotel in the past 12months
If you are looking for last minute things, there's always the sites like:
www.lowestfare.com
www.lastminutetravel.com
and of course the standards, travelocity, orbitz, etc
If you are just thinking about a trip, or "if I see a good deal, I'll go" I suggest going to your preferred airline's website and subscribing to their "air deals" newsletter. To do this, you simply join their frequent flyer program (its 100% free & you only get the email you ask for) and then subscribe to their travel deals email.
For American Airlines, for example its
www.aa.com and their program is the aadvantage. You can sign up for their letter, it comes out frequently but they always have good deals for both domestic and international. Delta is
www.delta.com and is their skymiles program for another example.
These newsletters contain the very best prices for the selected destinations. You can also setup other services to be alerted. If you have ever heard of the "tuesday at midnight, get the best deals..." rumor, its true but these newsletters tell you want that will be and on days that might not be tuesday
For example, this morning I got one from Delta. Roundtrip from New York (JFK) to Richmond VA for $69, came out to like $80 with tax or something crazy. You can't drive there for that between those two places... i do it often LOL.
They also have deals for hotels like other sites. Then again if you know where you want to go, find the hotel you want to stay at and check through their site for air deals. Most of the larger ones have some deals with airlines to help get people to their hotels.
Just some suggestions from a road warrior