When I smoked, all of my friends and family knew I did - I made no secret of it. I smoked in the house, in my car, basically anywhere that smoking was allowed. As a vaper, I do the same. As penguiness said, common courtesy (and sense!) is paramount, so I don't vape in stores, theaters, restaurants, etc. - basically anywhere that it might bother somebody else. I have no desire to be militant about it, anymore so than I was with smoking - but I won't hide it either. Sometimes being furtive and sneaky about it imparts more of a sense that you're doing something wrong/illegal to an onlooker.
As an aside, I have many non-smoking/non-vaping friends who have no problems whatsoever with me vaping in their homes and/or cars, whereas they never in a million years would have tolerated me smoking in them!