As far as the Blue Cash Preferred
I believe you get 6% back on grocery stores 3% on gas stations and 2% back on department stores.
Self explanatory I will help you. Walmart and Target are not grocery stores, since you live somewhat near me these are the stores that American Express categorizes as grocery Shop Rite, A&P, Pathmark so whatever you buy, magazines, food, wipes. It doesn't have to be burgers, soda, apple juice, milk, or eggs. Just anything you buy in a grocery store like Shoprite, Pathmark etc.
Gas I think has to be stand alone stations. In other words I don't think you get 3% back at Costco. It's suppose to be stations like Exxon/Mobil, Shell, Sunoco, Getty, BP, Hess, Citgo etc. However if you're down south and you go to station that's a 7-11 or Arbys, Subway I'm not sure if this counts I would call the number on the back of your Preferred card and ask them this question.
Department store are not Walmart or Target. However Kohls, Macy's, JCPenneys, Saks 5th Avenue, Nordstroms are department stores. Whatever you buy or if you want to get something in their cafe, it's all under department store. It doesn't have to be cologne, jewelry or cosmetics. You can go to Macys and buy wallets, belts, pants and they would qualify for 2% cash back on your credit card.
Best service for the Premier Rewards Gold Card
would be the airline tickets, but you said you only travel once a year. Another great benefit is if you go to a lot of rock concerts, Broadway shows, where you need to get tickets before they go on sale to the public, Gold Card events can help with some.
If you don't use any of these perks I would suggest the Green card. The annual fee is 95.00 not great but a savings of 80.00 a year vs the Gold Premier Rewards. Since the first year is free stay with the Gold, after the year if you don't have a need for a lot of shows and concerts and since you don't travel on business, I would just get the green card.