AP discount or general public discount

[M2DD's]

Were going to disney the last wk in May and the first wk in december.Will have a total of 18 park days and are going to be staying on property without a car(don't need to use AP parking discount). Which way is it cheaper to book our vacation.Using an AP discount for room or a MYW package discount. They have been offering package discounts the last 2 yrs for the dates were going. Is there any way to figure out what will save us money. We will be staying at one of the value resorts both times. There are 2 adults and 2 kids under 9. Any help out there!
TIA
Laura