We smoked in the bedroom when the kids were young, but now that they're adults it's a free for all.
We have seven kids between us. Three are in their twenties (25, 24, 20), one is 18, one is 16 and the two youngest (girls) are 11 and 10.
The adult kids are OK. The two eldest openly admit to smoking and choof up with us when they're around or in town. The 20 year old has smoked, but has only had the odd smoke with us. She's cool.
The 18 year old ( a boy), doesn't smoke anything and has some 'issues' with tobacco smokers

. We tend to not discuss weed or smoke around him, just to respect his feelings...Ph03nix just said he wants to be a cop... OH NO!!! We've failed as parents!!!!
The sixteen year old (a girl) really doesn't care what we do, so long as we give her some space to be 'her'. She is a good kid, but cherishes her freedom. Much the same as Ph03nix and I did when we were that age. We only smoke in the bedroom because of our two youngest. They don't need to see that their parents are doing what 'some' people consider a terrible thing. Like hypocritical former dealer fathers.
When they're old enough that they ask (I'm sure they know what goes on in the bedroom), we'll tell them honestly and probably assail their little brains with pot facts til they walk away and never ask again (they'll probably start a chapter of NORML once we've finished with them).