But things like chicken thighs ($1.39 / lbs at Costco vs $1.49 / lbs at the local grocery store)…I don’t think it’s worth the price.

2 things:

1. The chicken you get at Costco is probably a better quality, and generally you get more actual chicken per pound. Google "air chilled vs water chilled."
2. Get the things there that make sense for you. We like calrose rice in this house for a lot of stuff, go through quite a lot of it. At costco, the gigantic bag is like $20 compared to a tiny little bag that is $10-$12 at the cheapest regular grocer.

Combine those factors and I think it's worth it. I have things that are "costco items." Bulk spices, rice and some grains, dog food and treats, chicken, paper towel and TP, plastic wrap, hot dogs, pretty much any cheese, laundry soap, frozen convenience foods (dino nuggets, kirkland pizza, eggos, etc) and even some produce. Anyway, I go maybe once a month, and I've done the math many times over and it more than pays for itself. I wish I lived closer, because there are some things that I would buy more frequently that are way cheaper usually - milk, eggs, salad mix, fruit, etc.

But yeah, this is a 6 person house, with 3 adults and two teenagers.

Oh, last thing. Buying quite a lot of things at Costco is basically like buying an extended warranty or insurance. If you're going to buy a TV, for example, and Costco sells something that's close, buy that one. The OEM is going to offer a 1 year warranty, Costco will take that return for much longer.