My main bike and road bike that I ride 120 miles a week on is never locked up as it is never left unattended outside. It is either always inside when at home or on the road I'm riding it or if stopped somewhere it is by my side at all times. I live in a very friendly bike friendly area so I even take the bike with me inside the store if needing to stop to buy something.

For just running errands and the such I have a very old steel mountain bike that I lock up with a simple lock and cable.