Costco EVOO here too; about once a year they have Tuscan EVOO under the Kirkland brand which is very good also, and just a little more expensive. I usually always pick up a bottle of TJ’s Greek olive oil when shopping there. We buy special olive oils from time to time for dipping or finishing a dish.
You may want to try California Olive Ranch EVOO’s. We used to get it from Costco too when they had a shipment. I don’t see it there anymore unfortunately and it’s somewhat pricey if I run across it at the supermarkets.