Bharatpur... for a bird watcher like me is a dream place to go to. I have been there a number of times at different times of the year. The best time to go there, in my opinion is Christmas week and later right to middle of February.
There are a number of good hotels... my choice is the Birder's Nest which is close to the Sanctuary.
The best part of the visit is that no gas or diesel vehicles are allowed in the Keoladev Bird Sanctuary. You either go around the Sanctuary in a Pedal Rickshaw .. which is driven by persons who have by experience become experts in the local bird life. But it will be a good idea to take the services of Guides who are accredited by the Forest Department. You can also hire bicycles to go around and if you fit enough.. you could walk. Wear good walking shoes.. the distances are long.
Carry your standard bird watching gear... good binoculars and camera with good lenses.
You can see a wide variety of birds .......... Painted Storks, Open Bill Storks, Spoonbills, Cormorants, Darters, Ibises, Moorhen, Pheasant - tailed Jacana, Purple Coot, White-breasted Waterhen, Paddy Bird, Night Heron, Comb Duck and Dabchick, and a large variety of migratory birds such as Ducks, Geese, Raptors, Waders, Warblers and Cranes. I was lucky to see the last pair of the rare Siberian Cranes which visited India in 2006.
If your are a birder, you will have a great time there.