I use a SIM Pins with my iPhone and you don't have to power cycle the phone to activate it. You just stick a SIM in and the unlock screen pops up. Quite easy.

I should use a screen lock password, but it seems to be far too cumbersome to have to enter it 50 times a day.

What I need, is a one-button way to lock the iPhone. I would expect someone has written an app to do that, right?