Hawaii you want to stay, what you are going to do while
While the above search engines are great, they do not always include small airlines, especially in less popularly booked routes and/or in remote regions. If you're flying somewhere obscure, Google search and ask around if there exists a local airline. While in South America we learnt that the LADE Air in Argentina (run by the military) has cheap flights to Patagonia, which is of course not listed in mass search engines online.
This will give you a ton of options if you are traveling
Search at the right time. Turns out, there is a best time to search for flights. After several studies of domestic (to the US) air carriers, it has been determined that the best time to search for flights is around 3:00pm Eastern time on a Tuesday. Why? Around this time is when airlines release their discounted flight options, and look to fill up last-minute flights for the upcoming weekend. Therefore, save your flight searching for a mid-afternoon break on the nearest upcoming Tuesday.
If you're looking for true Americana, your choice is clear: road trip. Will you drive the soothing ocean view and coastal mountains Pacific Highway Route 1, or the truly amazing Beartooth Highway in Montana/Wyoming? How about the Sun Road in Montana through Glacier National Park, or the technically challenging Tail of the Dragon in Tennessee/North Carolina? Or will you tour the Main Street of America itself: U.S. Route 66?
While many theories exist around booking specifically on a Tuesday to save money, the reality is there is no consistent truth to exactly which days are cheapest to fly. Most of the time it is cheaper to leave on a weekday, though this isn't always the case. Your best strategy is to get a quick visual of prices for a whole month to see what days are cheapest for your specific route. Here's how: