Cottesloe beach is a good one here in Perth. Love the white sands and pine trees growing from the dunes hundreds of metres back giving great shade.
Good thing about W.A. is that you can go a thousand kilometres or more north, or south east and have a beautiful aqua seas and broad white beaches of your own, and not be disturbed from your hammock.
As for surfing, there are a few places in Margaret River. There are some great beaches in the eastern states - not sure if they get crowded or not. Too hot in summer to be looking for parking or to be queueing up.
Being the west coast side of things, its hard to pick only a handful of beaches - like picking a grain of sand out of a bucketful.
Cottesloe is nice, and I always like the white sandy beaches along on the west coast.
The best combination of aqua water and white beaches I have seen was around Esperance facing the southern ocean.
Top 5 ?
1. Cottesloe - love the pine trees along the dunes for shade, and the mixture of fishing and sun bathing.
2. Cant think of the name of the beach, but its comes directly off Esperance.
3. Scarborough - same reasons as cottesloe.
4. Nice beaches near Cervantes - just before Geraldton, good if you have a boat, some little islands around to add to the scenery.
5. Hillary's boat harbour, if your idea of being near the beach is little bit of sand, plenty of salt air and enjoy shopping on boardwalks with a casual and fun atmosphere and good sun and water slides etc.