I had access to flight information through an API that my work pays for and I rarely care exactly what day to arrive or depart. So I created an application that would dump all flights to a destination over a range of leaving and return dates. It dumped all the data into SQL database so I could filter on price, number and duration of layovers, class, etc. It was incredibly useful for really dialing into what I wanted (no layover over 3 hours, less than $X, etc). Using Google flights is painful by comparison.

Unfortunately I no longer have access to that API. The last time I flew I did this process manually and slowly discovered I should leave on a weekday and leave on a weekend for the best flight.