July Beach Time

Cádiz has a beach, so maybe that can be your beach time. Across the bay from Cádiz are Rota, Sanlúcar de Barrameda, and Chipiona. Each have beaches and the coast between Rota and Chipiona is nonstop beach. Any place you go along the Costa de la Luz or Costa del Sol will be full of tourists in July. I can’t speak to beach towns in the Barcelona area. Parking in the places I mentioned might be difficult that time of year if you’re just going for the day.

We went to the beach town of Sitges just south of Barcelona. It was spring (April), however, so it was fairly quiet there, breezy, and cool. Actually no one on the beach. I threw on my suit and dove into the water for a minute just to say I swam in the Mediterranean. We mostly walked around town and got something to eat and did some shopping. I imagine it must have quite a different scene in July.

Anywhere in Catalonia will be packed during July, especially on the coastline.

As for beaches, in the immediate north and immediate south of Barcelona, beaches are "nice" but not especially "beautiful" or "breathtaking", for that you should go a bit further north or south of the city, yet within Catalonia, which means that with a two-hour drive max from Barcelona you can enjoy this https://costabrava.org/en/ or this https://costadaurada.info/en and https://deltadelebreecoturisme.com/en/

The Atlantic beaches around Cádiz are truly superb. Much better than on Costa del Sol. If you have a car, you could check out the beaches around Conil, los Caños de Meca (Cape Trafalgar), Zahara, or Bolonia with the Roman ruins of Baelo Claudia. Chipiona and Rota also work, and are easier to reach, but more urbanized.

And if you want to keep things simple, the beaches of Cádiz are quite nice! They get quite wild as you go south.