Twenty of Nice's 25 beaches are just down some stairs from the Promenade des Anglais and, its extension, the Quai des Etats Unis which starts at Beau Rivage beach. For Coco Beach and the beaches east of Nice's Port, access is via the Boulevard Franck Pilatte and Avenue Jean Loraine.
For parking, you'll do best on the less-visited Coco and surrounding beaches. All the beaches along the Promenade are accessible by public transport but the easternmost stop for buses is the Jardin Albert Premier. The beaches east of this stop (Castel, Ponchettes, Opera, Beau Rivage) require a short walk. See more on Nice buses and Nice tramways.
Buses 12 and 32 run the length of the entire Promenade from Carras to Jardin Albert 1er with plenty of stops along the way. To access beaches along the Quai des Etats Unis, take any of these or other buses to the bus stop Jardins Albert 1er and walk a few short blocks east.
Nice's tramway takes you within a short walk of the beaches along the Quai des Etats Unis. The closest tramway stop for beaches near Nice's Old Town is is Massena on line 1. For western beaches, line 2 offers easy access from the CUM, Fabron, Sainte Helene and Carras stops. For access to eastern beaches take tram line 2 to Port Lympia.