Perhaps this map will help you understand the layout of the Polynesian Village Resort and the Polynesian Villas & Bungalows:
DVC villas will be in three longhouses, but only two -- Moorea (#2 on the map) and Pago Pago (#1) -- will be open when you are there in May 2015. The third DVC longhouse, Tokelau (#4), will not be ready for occupancy until July 2015, after your visit.
At the time of your planned visit, you could be assigned to a Standard View studio in either Pago Pago or Moorea. If you are assigned to Pago Pago (#1), half of the studios will look toward Moorea and have a garden view, and half have a parking lot/monorail view. The parking lot view might not be too appealing to some, but not too bad if you have a car and want to have easy access to it while staying at PVB. Also, the Pago Pago studios overlooking the parking lot will have great views of the monorails.
The Moorea Longhouse (#2) have all of PVB's 72 Lake View studios. These Lake View studios are all on the side facing the Seven Seas Lagoon. Moorea's Standard View studios all face the opposite direction and offer garden views.
I'm not sure if either longhouse would be advantageous over the other for someone with mobility issues. As you can tell by looking at the map, the Moorea and Pago Pago Longhouses are on the east side of the resort. You will check in at the Great Ceremonial House (#7). Pago Pago is a bit closer than Moorea to the Great Ceremonial House, the monorail station (#10), and also to the Poly's bus transportation (#13), but not by much. Both Moorea and Pago Pago are a short walk to the Ticket and Transportation Center (#14); it might actually turn out that its as quick and easy to walk to the TTC to catch a monorail as it will be to walk to the Poly's monorail station.
Good luck and enjoy your stay. Please post back after your visit and let us know what you and your sister think about the layout of PVB.
