Each Savannah is seperated and has a different mix of animals. That said, I'm fairly sure all 3 Jambo savannah's had Giraffes (Jambo and
Kidani share the Sunset Savannah). I am not sure if the Pembe is missing the giraffes and/or Zebra's in favor of a different animal..
From a recent report, Sunset savannah now has the most giraffes (they possibly moved some from another Jambo savannah) From my experience, I saw the most animal and Giraffe activity during evening feeding time. (It was possible to miss seeing any animals in the AM)
Disney does space feeding areas around the savannahs so animals do eventually make the "rounds" to everywhere, but here seem to be sections / alcoves that certain animals generally congregate in during non-feeding times, meaning some sunset savannah rooms may have near-continual, close giraffe viewing, and other rooms only see them a few times a day...