Assuming you will be trying to book when the seven month window opens for your trip, I very much doubt that VGF will have any studios available during your travel dates. If you want to travel during late November and Christmas and stay at VGF, then you need to book as close to the 11 month window as possible.
The same is true with BLT Standard View, which would be your cheapest option, points-wise, at the three monorail resorts. Even BLT's Theme Park View could be very iffy at the seven month mark.
That will leave you with only two options at the seven month window: BLT Lake View or PVB studios. With PVB being so new, its hard to predict whether its Lake View category will have strong demand before the seven month window opens. However, I doubt it because there are 72 Lake View studios at PVB and, at least through 2016, much more of PVB will be declared and available for
DVC bookings than what has been actually sold to PVB owners (Note: right now 40.7% of PVB has been declared but only 18.2% has been sold).
PVB Standard View is just a little bit cheaper than what BLT Lake View will cost you during the Adventure Season, but PVB Lake View is much higher. PVB will offer you more space. Plus, PVB has the pull down Murphy bed, so you actually have three beds in the PVB studio to accommodate your family of four. At BLT, you only have the queen bed and the sleeper sofa, so it will have to be two in the bed, two in the sofa.