Costco is one of those places that the membership is worth it if you use it. Their gas is incredibly cheap here, but not important if you don't drive. Their rotisserie chickens are the cheapest around and great for multiple meals. I think there was a thread not too long ago, maybe the W30 one, about the best things to get there. We go regularly for milk, bread, carrots and gas, but tend to stay away from their produce as it always goes bad really fast.
I'll have to look into the Chase Freedom Visa for more bonus points, but as it stands right now, we are set to get back over $100 in cash back for the year for using their Citi branded card (formerly AMEX). As for the membership dates, it's day-to-day: sign up on October 15 2016, your membership is good until October 14, 2017. I tried switching to Executive (2% cash back on everything you buy at Costco, on top of the credit card bonus) but we didn't earn more than the extra cost, so they dropped us back to regular and refunded the $55. Which leads to another point, they are amazing about returns. We are on our third printer in 8 years, no questions asked.