In the car, I never really have much more than I'm going to smoke while in the car. If I just did a pick up, I simply leave it in the center console. Why? Because I'll be obeying the traffic laws until I get home so I don't have to worry about getting stopped.

At home, it depends. If I'm in the midst of a time where my wife has given me her blessings to smoke, I just leave it whereever. If I have to smoke behind her back, then I tend to keep it on my person or in a winter jacket that doesn't fit that's hanging in the closet.