When is the least expensive time to go to Hawaii? Specifically Kauai? Depart DFW or HOU.?

I would look at travel dates around mid-September to early November as well as February through May. June-August is peak travel time and will not be cheap. Check out a href="http://www.kayak.com" rel="nofollow"http://www.kayak.com/a and sometimes you can save money if you buy airfare, car rental and hotel as a vacation package. That is what I did when I took my wife to Kauai for our honeymoon.