I guess I thought it was a rule of thumb that nothing orbiting a gas giant is likely to be worth much of a peek. I just finished scanning a system that featured a Class III Giant which had three high metal planets (two terraformable) and a water world, also terraformable. Its neighbor, the Class II Giant, had three high metal planets. This trinary system also featured a couple of metal rich planets, a couple of high metal planets, and two more gas giants with rocky moons.
One pic:
One pic: