we have an area in the living room, where we spend most of our time.. it is kinda in a corner.. by the bathroom. And we have another one in our bedroom (where we all sleep!) so if they are in one part of the house, they have one.. if they are in another part, they have one there also! i would just put them where they will be easily accessible.. yet as discreet to company as possible.. in a corner, etc.
im sure the switch will be fine.. just be consistent and i dont think it will be a problem(if she is already pee pad trained!)
good luck!