You also have to pay for parking- about $40 per night at the resort or about $20 per night at a local lot about 1/2 mile away.
If you like to walk, there is a lot to see in the downtown area that may cover a couple days. Balboa Park, which hosts the world famous San Diego Zoo, and some museums is walkable if you are in good condition. Otherwise, it’s a short ride away. There are a lot of restaurants in the Gaslight District too. And if the Padres are in town you can catch a game or two.
However, for the beaches, Coronado, Sea World and anything else you would need a car. If you don’t want to rent a car for the entire time you could rent one on specific days. There is definitely much to see and do outside of the downtown area.
Best regards.
Mike