You can always request to be in a certain building/area depending on your room type (I.e. you can't request a preferred building if you don't have a preferred room reservation.) You can find building numbers on resort maps so you can figure out what might be best for your family. They do try to honor those requests, but sometimes they just can't.
In my experience, about 5-7 days before your arrival is the best time to call and have those requests added to your reservation.
Hope this helps.