seatguru.com
Google Flights
airfarewatchdog.com
trivago.com
Kayak.com
Master Card benefits
Hotels.com
Quickbook.com
Expedia.com
Orbitz.com
Travelcity.comm
http://www.cheapflights.com
Priceline.com
http://www.bookingbuddy.com
Hotwire.com
TripAdvisor.com
Travelaxe.com (compares rates on other sites)
Travelworm.com (for casino rsorts)
Hopper - flight deals
FareCompare - flights & hotels
The next three are discounts around Disney world:
Disneydollarless.com
Mousesavers.com
Wdwig.com
Unusualvillarentals.com (3,500 pages on villa rentals)
Hiddentrails.com (affordable dude ranches etc)
Lastminutetravel.com (unsold hotel rooms - discounted)
11thhourvacations.com (unsold hotel rooms - discounted)
Caribbean-on-line.com (reviews of 1,000s of Caribbean resorts)