The coast Costa Smeralda is known for its beaches.
We found an apartment in Golfo Aranci at Villa Marconi (41.008272, 9.615173). There is a nice apartment on the top floor, with a large terrace, but you have to search for it on google, since it's not often on booking.com. You must have a car to stay at this location.
Of course, from a logistical point of view, it would have been more convenient to stay in Olbia, but Olbia is not a tourist city and we did not even consider it. And we would not have seen such sunrises there.
There are several beaches in Golfo Aranci, a small promenade and restaurants, and in general the town is quiet. The movie The Little Mermaid was filmed nearby. If you're interested, it was filmed on the beach of Spiaggia di Cala Moresca (40.987595, 9.646758).
There are several pizzerias where we had lunch. We also visited Maman Ludì restaurant (40.789462, 9.167688), stopped on the way to Alghero. Though it's relatively close, so you can go there from the east coast. A very unusual place on a mountain, with a beautiful view.
We did not swim on the beaches in Golfo Aranci and instead visited many of them on the Costa Smeralda. There are a lot of sandy beaches here, the closest is La Spiaggia Bianca (40.991126, 9.591479). Almost all have free and paid areas, with sunbeds, snack bars, toilets. I did not notice any particular difference, the water is clean everywhere, so open the map, choose any and go ahead.
There are two roads leading from Golfo Aranci to the beaches and the main road. Whichever one you take, you will pass excellent viewpoints. One here is 41.001386, 9.581106.
Second is here 40.998583, 9.592318.
Getting there: Golfo Aranci is located near Olbia, the village has a large ferry dock and a railway station.