I can't help you with your specific requirements, but I'll tell you what I tell everyone looking for the "best price possible"...
1) Start stalking airfare prices now. I'm going to suggest using google.com/flights. They can look at multiple airlines, and multiple airports. Just know, often the fare they return is a "basic economy".
2) Know that the price for nine might be different than the price for one. I always do my checks based on the price for one, knowing that when more people are added, it MAY increase the cost per passenger. In which case, I also know I can make multiple bookings (maybe one for four, and another for five, with the second one in a different "fare bucket"). If I do multiple fare buckets (I haven't had to, but I know the possibility is there), I'd make sure there's at least one adult in each fare bucket. That's just in case of flight changes when not everyone can get onto the same new flight.
3) Set yourself a target that if the prices get to, you'll purchase. This shouldn't be the "ideal" price, but a "comfortable" one. If you book with an airline that doesn't have change fees (SW, Delta, Alaska), keep watching the prices after you book. If the price drops, do a "change" and get at least flight credit. If you book with an airline that does have change fees, and will be upset if you've spent more than you need to, don't look again.
4) Also know that non-stop flights and those departing between ~8a-5p will be more expensive than the early flights or later ones. Accepting a layover and/or leaving early/late could save some money. We're talking the family on a cruise in July. The flight I *WANTED* left at 10:30a, had a connection, and got in at 3:30p. However, it was $600pp. The flight I BOOKED was 6:30p-1030p, and was $377pp (big difference, especially with 8 people). Delta changed flight numbers for the 6:30p so I was able to move everyone (at no charge) to the 10:30a flight. That flight is now selling for almost $1k.
@jec6613 has a good idea about the weather.