Half Moon Bay is great isn't it. So is Safety Beach - agreed.
Some of the best beaches can be found in Melbourne South East, the stretch of beach between Edithvale to Seaford are some of the best in my humble opinion. Chelsea - Carrum with is vast white sand beautiful sea, and not crowded at all, also great that all of these beaches are on a train line too.
Mornington Peninsula for more great spots including any one of Mornington’s beaches, or down to Portsea. Also Balnarring is beautiful, but for these beaches, a car is needed.