The best time to Hampi would be between October to February. Actually anytime after the rains have started.
We went to Hampi in end Jan early Feb. The first thing we did on arrival was visit Mango Tree restaurant for a sumptuous vegetarian meal.
Walk around Hampi is in two parts,the Temple complex and excavations at Vijayanagaram. The latter is now declared as aUN Heritage sight.
Temple complex walk starts at Ganesha temple and ends at Ugra Narasimha temple.
Here are some pictures of our trip to Hampi.