If I could ask for one thing, that would make a gun store way more than just somewhere to spend money, I would ask for a social corner.
Ever go to one of those book stores that has a coffee bar over on one side of the store? Something along those lines.
It would not need to be very large, and the coffee need only be Folgers with a little cream and sugar available. I'm sure most people actually would put $.50 in the jar and you would at least break even on the coffee.
Cookies! Store bought would be alright but if you could bring in home made I would pay a buck a cookie to go with my coffee.
Chairs wouldn't need to be very nice, skip the couch though.
Maybe a coffee table with last months gun magazines laying around for people to thumb through. (Have this months gun mags. for sale in a proper rack.)
See, I can go pretty much anywhere to buy a new gun. If I really want to save money I'll buy used on line and have it shipped in. What you can't get from the internet is somewhere to talk to other gun lovers(in person), flip through magazines on hunting etc., have a cup of coffee, and then grab that box of ammo you need for the upcoming range trip.
Ever see how willing guys are to linger in a Fun Store even when it's obvious they are finished with their business? It's 'cause we just like being in there. Give us a spot to sit, out of the way and not bothering anyone, and we will drop in there pretty much any chance we get. We will, of course, buy a little something while we are there, even if it's just a brick of .22shells or a pack of paper targets; even though we don't really need them.