When we checked in on July 30, at about 11:30 am, I had a savannah room reserved, had requested zebra trail, arusha savannah, nonsmoking with bunk beds --and had asked, if possible, to be on third or 4th floors in at least the 3rd section of rooms out.
They had preassigned us a room on zebra trail, arusha, but it was the first room off the lobby on the second floor with a view of nothing but arusha rock.
I was just opening my mouth to try to argue that I wasn't paying for "rock view" when my 9 year old DD took a deep breath (she was standing with me) and said, "Please, do you have any room that is further away from the lobby on the third floor? We'd really be willing to wait." The CM had a soft spot for her, and did find us a room--not an upgrade, but did reassign the room. I think if my DD had not been with me, I might have been out of luck.
It certainly would not hurt for your child to accompany you to the desk, and ask about the best places to see the animals. I could be wrong, but in watching people check in over the week, it seemed to me that upgrades went more often to families with wide-eyed children. I'd also suggest that around 10:30 am or so lets them know who's checked out, but they still have some inventory to play with.
Just my 2 cents worth.