For Hong Kong, if you just visit several famous attractions, 2-3 days would be enough, but if you want to do some complete tour, I think 9-10 days won't be too much. Also for Macau, at least 1-2 day is enough to tour around Macau. In Hong Kong, you must go to the Disneyland, Ocean Park and Ngong Ping 360 Cable Car and the Peak. In Macau, you must go to the Ruins of St. Pauls, Senado Square and Venetian Macau.