I guess you either have to be lucky (it happens) and check at just the right moment, or you have to check constantly. I usually book accomodations and flight separately and have always done better. I have seen and heard of packages deals that were better.
Even doing it separately, checking constantly can have great dividends. I checked one day when I was getting ready to go back to work....mid afternoon and there was a delta flight Round trip from NH to LV for $100. Never seen it before or since and it didn't last long.....I guess they had a few seats to fill and when they did,....it was over.
Well, for those who are patient and determined (or those very lucky) there are some great deals to be had. Just keep checking!!
Jim