Another thing to consider is facilities in the room. Will the newborn be bottle or breastfed? If bottle fed, you might want a room with kitchen facilities, like a studio at a DVC resort. Of course, this gets expensive. Personally, I would chose a resort that is a little less visually stimulating so that going back there is more restful for the baby. WDW is SO stimulating that a little baby really needs a break -- I'm thinking a moderate might be better in this regard. Also, if you are going to be using a crib rather than co-sleeping, you might want to consider a moderate since the rooms are bigger than value resort rooms and therefore you won't feel as crowded with the crib in the room, too.
I know you didn't ask, but I would definitely recommend bringing your own stroller and bringing your own crib sheets (portacrib sheets or pack & play sheets).