My favorite beach would be Corona del Mar state beach. There are bathrooms, snack bar and nice sand. Paid parking lot is right on the beach so you won’t have to walk far at all. However, it can get filled up fast so I would get there no later than 10:30-11:00 on the weekends. Alternativly there is a drop off area in the parking lot, so you could always drop off people then park in the free area in the neighborhood before the parking lot. This can also get filled up though if you get there really late and you may need to park farther away and walk like 5-10 minutes.