First and foremost for me is friendly staff, and imperative to me that the sales rep knows the ins and outs of vaping as a whole, I have learned a lot from hearing reps talking to other customers. I don't want to hear biased opinions on various tanks, mods, set ups. When I go in looking for "something" I don't want to be pushed to buy a certain mod/tank/set up just because it's the newest and latest thing. I understand trying to make a sale, but if I'm not interested in a 200w mod, stop with the pushing. The B&M I frequent has an awesome guy (he's the owner) and he will steer customers to the BEST set up for them. He makes recommendations but doesn't get pushy.
As for products: I like to see a range of "stuff", from Ego batteries to the high end mods. I like to see a variety of simple Ego tanks to rebuildables, as well as the high end tanks/drippers. Having a variety of coils, and the supplies that go along with rebuildables. Nothing insures that I will never return to a shop quicker than stopping in for say: cotton bacon and asking for a particular wire than hearing: "Oh, I don't carry THAT. I hate that stuff". Tells me they are more interested in selling their favorites than what appeals to a variety of customers. And a variety of juice brands. Because juice/flavors/PG-VG ratios are as varied as the people who use them.