As others have mentioned flexibility in destination is key. As a family of 5, we don't really look for a particular destination that we must be locked into. Using the award tickets primarily for vacations, we see what is available at what redemption rates and we go there. The world is a pretty big place.
Other points which have been mentioned but I will +1
-Diversify your award programs to include a couple alliances.
-For domestic, think Southwest. Companion Pass is great. No change fees. In the last 18 months we have booked MCO, FLL,DEN,MSY,SEA