My two cents.
I hate the habit of smoking. I've never had a cigarette in my life. I have been tempted on occasion, but I feel it's really not worth the financial and health problems. Really, that's all that keeps me away.
Alex smokes. At social occasions, she'll smoke quite a bit. I don't have a problem with this. I'd like for her not to smoke, but I'm not about to dictate her life. The only thing I would dictate is no smoking inside my house (whether it's her's as well or not). She's lived in a couple of houses where they permitted indoor smoking and I hated being there. Even she hated it when everything of hers smelt like smoke. I always encourage her to smoke less, with little results. It's her decission ultimately. The only thing I am against is when she smokes just before meeting me. It makes romantic greetings less pleasing. But that's a personal reason.
Most smokers I know are considerate. They ask if you mind while you're eating. They try to keep the smoke out of the way. They make sure there's ventilation where they smoke. The only thing I see them not be considerate about is pinching other people's cigarettes!
Ultimately, my view is let them do it on their own time, with their own health and money, on their own private property.
One thought to help stamp out smoking: put smoking related illnesses in the same category as elective surgury. They elected to partake in the deadly activity afterall.