www.LongIslandNewConstruction.com ,   www.LIHorseProperty.com , www.LongIslandSeniorsHousing.com , www.LongIslandGolfProperties.com,   www.LIHomeAuction.com ,  www.LIWaterfrontProperties.com , &  www.PrudentialElliman.com ,  www.prudential.com/realestate . Manhasset Hills Information Manhasset Hills is a hamlet (and census-designated place ) in Nassau County , New York , United States . The population was 3,661 at the 2000 census. Manhasset Hills is