Grocery stores would be great with a Generation-themed EP, or as others pointed out, a Farm Life GP; more so with Generations, as Farmer's Markets would work best for a farming pack.
I'd definitely love to have different departments in grocery stores. Since we're getting a florist game feature in Seasons, and we also have the ability to own bakeries from Get to Work, being able to have a bakery, a deli, and florist in grocery stores would be amazing. Cashiers could multi task- ring customers up, bag groceries, clean aisle spills, and stock the store. And then we could have 3 additional staff slots- butcher, a clerk that worked in the deli/bakery, and a florist. So all together we could have 6 total.
I'm also hoping in the future we get a Ice Cream Shop stuff pack with frozen yogurt, milkshakes and sundaes, with the ability to create our own ice cream parlors- would be a great addition to summer-fun activities, but that's for another discussion.