Understand though that the animals are not going to be standing right outside your balcony 24 hours a day.
They come and go and depending on when you are looking you might see them and then you might not.
I just know that some people have commented before they were disappointed they did not see as many animals as often as they thought.
And there are plenty of viewing areas if you don't get the Savannah view.
We actually got lucky during our recent Sept 1st-8th trip. We booked a pool view room and requested Zebra Trail. When we checked in, we had been upgraded to fantastic second floor Savana view, facing the Arusha Savanna. It was the perfect room. If you go straight across the lobby like you are going toward Arusha Rock, then go down the metal stairs to the right, (again like you are going out onto Arusha Rock), then glance to the right you will see a hallway that leads to rooms (just past the round observation area). We were the second room down that hallway (just as you start up that hallway you can see the small slope and we were right at the top of that slope). Anyway we were on the second floor (first floor of rooms, since the Savanna is actually the first floor). Anyway, there were four or five giraffes, two zebras, and an ostrich that stayed just below our window all week. I always thought the animals went into their barns at night, but several nights when I couldn't sleep, I'd step out onto the balcony and was able to see at least two giraffes every single night, just below our balcony. They stayed there all week.
Our room was seconds from the doors that lead out to Arusha Rock and from the back of the lobby if we used that staircase, but just before that hall ended, next to that area that leads out to Arusha Rock, where the two staircases start that lead up to the lobby, there was a short hall that was the lenght of the lobby and went back toward the bar and if you looked over the railing you could see the check in area of Boma, just before you got to the elevators, so we were only a minute or two from the restaurants also. I think the room may have been 2409--anyway is was on the floor closest to the Savanna, second room in the first pod of rooms. I actually felt sorry for people who were on the opposite side of the savanna, because for some reason the giraffes pretty much stayed over on our side of the savanna all week. We never looked out that we didn't see them there. I got a great AP discount for a pool view room, that I would have been perfectly happy with, but got a free upgrade to a perfect savanna view of the Arusha Savanna with a room that was close to everything.