Depends on how much your bikes are worth, really.
Mine are just as secure as anything else in the house, protected by the alarm system. I don't lock them up any further. It's not like I have a D-lock around my TV.
If I had one worth over £1500 I'd probably take special measures, as apart from anything else, the insurance would require me to.
Out and about, I take a cable lock if I think I'm going to be stopping.