A short trip Rakesh with a demanding shopping list. :S3:
Lake Nakuru is good, you should see Rhino there, but obviously the key element is the large number of Flamingos. Samburu is also good I have found. Personally, with the limited time you have, you want to spend as little time getting around to several locations and use one area as a hub, so to speak.
There are a couple of other locations I am looking to work out from
- Kicheche Mara camp
- Little Governors camp
- Rekero camp (superb, but at a price)
You could also contact Ken Dybal too, he is based out in Kenya