The only park AKV is particularly distant from is MK. It is bus-only to all parks, which has people exaggerate its distance.
Poly is close to MK, but is further from other parks. The monorail connection to EPCOT can be an issue, actually.
DTB did a head-to-head on AKL vs. WL the other day. Quote:
It thus might come as a surprise to learn that Animal Kingdom Lodge is closer to more parks than Wilderness Lodge. In fact, once you get past the boat transportation to Magic Kingdom, Animal Kingdom Lodge is more convenient to each of the 3 other parks and Disney Springs. Yet, the myth about Animal Kingdom Lodge being inconvenient/isolated persists, probably at least in part due to perception.
http://www.disneytouristblog.com/wilderness-lodge-animal-kingdom-comparison/
While this is a comparison of the Lodges, not of AKL and Poly, it remains true applied to Poly.
I would say, though, that when Poly's an option you're talking studios. If you're pricing studios, be sure to price Standard or Savannah at AKV. Value is probably not an option, and Club Level definitely isn't. AKV will have 1 queen bed and 1 double sofa sleeper that sleep 4. Poly will have 1 queen bed, 1 queen sofa sleeper, and a pull-down murphy bed that would probably work for the 11-year-old, but probably not the 18-year-old. So either way, it's important to understand only you and your DH will get a "real" bed, and reports vary on the comfort level of the two other bed options. My 5 year old and 8 year old were okay with the sofa bed and murphy, but I'm pretty sure they'd sleep on beds of nails at a hotel. They love hotels and condos and timeshares with a weird glee, even if they're not at Disney.