Honestly, not just bars, but any private business proprietor should be allowed to choose whether or not to allow smoking, so long as it's reasonable... bars certainly fall under that reasonable expectation, "Baby and Me" or a book store not so much.
But I don't think you should need to be a liquor store or have a liquor license to allow smoking, and I don't think that just because you're a bar that you should have to allow it. If you allow it, people can choose to go to a different bar that doesn't allow smoking if smoke bothers them.
If you're an old bumpkin hole-in-the wall discount grocery store, that's an arguable gray area, especially if you're the only grocery store in a reasonable distance in a rural area where people couldn't reasonably give their patronage to a different store. If you're a hole-in-the wall watering hole and the only one within reason, then it should be allowed if the owner wishes it even though there's no reasonable alternative bar people could go to. The difference is, people need groceries and food, they don't need to drink alcohol at all, let alone in a bar (and that's not some moral anti-alcohol thing, that's reality, drinking is a luxury and not a necessity).
Basically, it boils down to common sense. And of course I'm not against banning smoking in public buildings (like, government buildings... post offices, courts of law, the local utilities department, etc), that's again a case different than a private business.
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