The numbers given actually prove the point of those who don't see a need for a complaint here.
OP has 6 family members, so they have the choice of a value suite, two rooms anywhere, or Ft. Wilderness cabins. They can't stay in one room anymore.
The $106 per night more for two rooms at POR than the ASM suite for nine nights would be $954 MORE and they are only paying $720 for the DDP upgrade. So, staying in the value suite and paying for the upgrade is cheaper than the two rooms they need.
Now, if they are at AoA, then it's only $56 per night difference, and that times nine nights would be $504, so it would be cheaper to do the two mods.
The cabins at Ft. Wilderness are $285/night in the month of Sept ($300 on weekends), so they could stay there for just a little more than the ASM suites and get the regular DDP.